Topic: FRUITS, SEEDS, AND PLANT REPRODUCTION

Source: A seminar presented in Central Illinois Saturday Science Education Seminars for Elementary Teachers

Presenter: Joseph E. Armstrong Department of Biological Sciences Illinois State University Normal, IL 61790

Funded by: Scientific Literacy Center Illinois State Board of Education 1990-1993

Abstract: A lot of good biology takes place around your house and garden, the trick is to recognize what is going on and how it relates to general principles of biology. The following activities in botany for the elementary classroom use fruits and seeds that are commonplace and important items in our daily lives. Investigating fruits and seeds is a good way to teach observation and promote an interest in science. These activities can be adapted to several grade levels depending on how they are used. Some activities will do well in earlier grades while others will serve grades 5 and 6, or even junior high. Technical terms have been kept to a minimum, and all can be found in large dictionaries and classroom encyclopedia. The emphasis is on observing, explanation, and testing, in other words, science.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

INTRODUCTION

Many fruits and seeds are commonplace and important items in our daily lives. Investigating fruits and seeds is a good way to teach observation and promote an interest in science. These activities can be adapted to several grade levels depending on how they are used. Some activities will do well in earlier grades while others will serve grades 5 and 6, or even junior high. Technical terms have been kept to a minimum, and all can be found in large dictionaries and classroom encyclopedias.

The emphasis is on observing, explanation, and testing. In other words--science. Teaching terms and definitions, and testing memorization IS NOT SCIENCE nor is it good teaching. Terms and definitions should only be introduced after students have developed their own concept or visual image, then they have NEED TO KNOW appropriate labels and terms. Far too much elementary science teaching places the terminological cart in front of the conceptual horse. In the traditional presentation/regurgitation approach to science teaching, students are passive learners. Comprehension, retention, and interest suffer accordingly.

The active approach to teaching science makes students directly responsible for making observations, offering tentative explanations, and testing those ideas. Taking advantage of students' natural curiosity and creativity improves interest, comprehension, and retention. The active approach to science teaching mimics the process by which scientific knowledge was originally acquired, which reflects how the human mind works.

The trick for teachers is to direct and guide activities and discussion, supplying information when needed. Like all skills, this style of teaching requires practice to make perfect. Small group dynamics often provide a very productive atmosphere for active learning. In many cases, elementary education teachers in particular feel constrained by a lack of fundamental knowledge of science. In this workshop I will supply you with some basic knowledge, perhaps to clarify what you already know, and offer suggestions on how to teach these topics using an active approach.

A number of references to botanical topics appropriate for elementary grade levels have been included in Appendix B. A good classroom encyclopedia can be a great assistance too. Don't be afraid to experiment on your own. Be observant, a lot of good biology takes place around your house and garden, the trick is to recognize what is going on and how it relates to general principles of biology.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

Table of Contents

Lesson 1 What's in a Seed?.....................................4

Lesson 2 How do Seeds Grow?....................................5

Lesson 3 How do Seedlings Break through Soil?..................6

Lesson 4 Do Seeds Know Which Way is Up?........................7

Lesson 5 How does a Seedling Know When it Gets Above Ground....9

Lesson 6 What Seeds are Around the House?.....................11

Lesson 7 Variation in Fleshy Fruits and Seeds.................12

Lesson 8 Why do Fruits have Skins?............................14

Lesson 9 Variation in Dry Fruits..............................15

Appendix A Seeds Around the House.............................18

Appendix B Botanical/Science Literature for Elementary Grades.19

Appendix C Worksheets Accompanying Each Lesson.............20-31

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 1 WHAT'S IN A SEED?

Background Information

A seed functions in the reproduction and dispersal of plants. Most of our familiar plants are seed plants, although you may not always see or be aware of seeds. All flowering plants and all of the evergreens or conifers reproduce using seeds. A seed is the product of sexual reproduction, and each seed contains an embryonic plant, which can grow into a new plant(s). Many seed plants can also reproduce using plantlets, bulbs, or other non-seed structures, but this involves only growth and so is termed asexual or vegetative reproduction.

Materials dry beans soaked overnight unsalted peanuts in the shell

Procedure

1. Ask students, "What is inside a seed?" Have them think about what happens when a seed is planted. If they guess a plant, have them guess about how big it must be (It must be pretty small).

2. Have each student carefully dissect a bean. First, remove the seed coat; it's protective function is finished when the seed germinates. Then have them observe what is inside, a bean embryo. They will see two seed leaves. Each half of the bean is an embryonic or seed leaf, a cotyledon (kot-ee-lee-done).

3. Carefully separate the two halves which are attached at one point. One half (cotyledon) will have the rest of the embryo. They should be able to see a curving root and centrally a shoot composed of a folded pair of leaves. The two cotyledons are bigger than the rest of the embryo. Why? To store enough food for growth until the seedling can reach sunlight.

4. Ask if they can find the same parts in a peanut. A peanut is also a bean, and all the same parts are present, except the root is shorter and straight.

5. Finish this lesson by having the students think about what will happen to these parts as the seed germinates and begins to grow. You may want them to write their ideas down for comparison with later observations. Have them guess about the following--What part of the seed will grow fastest and appear outside the seed first? What part of the seed will appear above ground first? What will happen to the cotyledons?

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 2 HOW DO SEEDS GROW?

Background Information

Most common seeds go through a dormant or resting stage. The first step in germination is to absorb considerable amounts of water. This activates the embryo, and using stored food, it grows quite rapidly. The root appears first, then the shoot. What first breaks the soil surface depends on the type of seed, but this can be determined through observation.

In corn the embryo only occupies a small portion of the seed. In a soaked corn seed, it appears as a light-colored oval area low on one side.

Materials variety of seeds (beans, peas, squash, corn) clear plastic cups paper cups paper towels vermiculite peat seedling starters several 1.5 liter clear plastic soda bottles (Why wouldn't green work?) Cut each soda bottle at the top of the black base.

Procedure

1. Have students count out a number of each type of seed (e.g. 10, 20, 30) and weigh them. Record the weights. Then soak the seeds overnight in water. Pour off the water. Carefully blot dry with paper towels and reweigh. How much water did they soak up? How many times heavier are the seeds? Do all seeds soak up similar amounts of water? Why soak seeds before planting?

2. Fold a paper towel so that when rolled into a cylinder it fits within a plastic cup. Loosely crumple another paper towel and stuff into the bottom of the cylinder to hold the paper towel out against the outside of the cup. Add an inch of water to soak the paper towels. Put 3 or 4 soaked seeds per cup about 1/2 way down between the paper towel and the cup. Use a 2nd cup nested within the first to gently hold the seeds in place. At the same time fill each paper cup 2/3 full of soil & plant 2 seeds per cup or pot under about 1/2 inch of soil. Water and place within your soda bottle greenhouses. Label all of the pots and cups. Have students make daily observations (3-5 days). Have students note the light-colored area on the corn seeds and place this on the outside when planting in the plastic cups.

Planning Hint: Start the seeds on a Friday. By Monday growth will have begun and observations can begin.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 3 HOW DO SEEDLINGS BREAK OUT OF THEIR SEEDS AND PUSH THROUGH THE SOIL?

Background Information

As seeds swell with water, they exert tremendous outward force. It can easily break open a tough seed coat (a hard fruit like a nut shell) or push aside the soil. The following lesson can be very dramatic, but is best done as a demonstration.

Materials metal screw-capped jar with holes drilled or punched outward (Best choice has long, low pitched threads) dry peas or beans to fill the jar larger jar or plastic bucket

Procedure

1. Challenge students to figure out how to break a glass jar using seeds. You can always bet them cookies or pizza or something that you can do, but this demonstration isn't a sure thing, so be prepared to pay off if it flubs. I hit it about 70% of the time.

2. Fill the jar with dry seeds. Shake and jostle them down so empty space is minimized. Screw on the lid firmly. Fill bucket or larger jar with water. Submerge seed jar into water and allow all of the air to bubble out. With some luck, the swelling seeds will break the jar. This can take a few hours to overnight

3. Do children still wonder why they aren't supposed to put beans in their ears or nose? What could happen if the seed absorbs enough water to swell up? (The bean gets stuck very tightly and removal can be very painful.) What can happen if a seed falls into a crack in the sidewalk or between bricks?

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 4 DO SEEDS KNOW WHICH WAY IT UP?

Background Information

Notice that seeds don't come with arrows or labels saying "This side up." Roots and shoots can sense gravity and respond accordingly. The mechanism is not well understood, but roots grow toward gravity and shoots grow away from gravity, no matter how the seed is placed. This is called geotropism. Since roots grow toward gravity, they are positively geotropic. Shoots grow away from gravity, and are negatively geotropic.

Materials bean and/or corn seeds soaked overnight plastic cups beakers or jars paper toweling

Procedure

1. Have students observe seeds and determine if/how they point them in different ways based on the seeds' shapes or markings. Beans have a scar on one side, and corn has a pointed end and a rounded or blunt end. Have them draw each seed as if these particular landmarks were pointing toward 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock.

2. Construct a seed germination chamber using the plastic cups and paper towels as in Lesson 2. Position 4 seeds equally spaced around the cup so that each seed points up, down, left, and right. Use a magic marker to put arrows on the cup indicating their directions. Observe daily over the next 3-5 days.

3. How does the root emerge in each position? Do they all turn downward? (yes) What do they think will happen if they turn the cup upside down? After making a prediction, let them try it. What happens to the roots by the next day? (They turn to point down.)

4. What would happen if the roots were growing straight down, then you turned the cup on its side? (Roots turn sharply downward.)

5. So does it matter how you plant your seeds in a garden? (No, except you can plant them too deep. But the root always goes down.) What problems could this produce for space pioneers trying to grow plants outside of Earth's gravity? (The seedling will not be able to orient correctly.)

Continued

LESSON 4 Continued

6. Do with advanced students. Ask them to design an experiment to prove that roots are positively geotropic. Ask them to stop and think about what produces a gravity-like force. If they cannot guess, demonstrate centrifugal force by swinging a weight around your head with a string. Gravity still exists, but the centrifugal force prevents the weight from falling toward the Earth. If you want to be real dramatic, use a pail of water. What would happen if seeds were germinated while similarly spinning? (The roots would grow out away from the center.)

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 5 HOW DOES A PLANT KNOW WHEN IT'S ABOVE GROUND?

Background Information

Seeds do not need light to grow initially, but their shoot must reach light before they run out of stored food. Light causes seedlings to stop rapidly elongating and to start making chlorophyll, so they become green only after reaching the light. This can be demonstrated in a simple experiment.

Seedling shoots also display a strong positive phototropism. They bend toward light very readily. This is why you have to turn house plants by windows (a unilateral light source) regularly to keep them symmetrical. Plants bend by elongating cells on the side of the stem or leaf stalk opposite the light source. This can be demonstrated by carefully placing equally spaced dots of ink or marker on a stem, and then remeasuring the spacing after bending. See how easy classroom experiments can be?

Materials bean or squash seeds soaked overnight peat pot starters or paper cups with soil soda bottle greenhouses

Procedure

1. Plant one seed in each of two identical pots. Water and place within a soda bottle greenhouse. Place one near a window and place the other within a dark cabinet. Don't peek! (You may have to check on water, but do it quickly and with the lights low. Or place the soda bottles in a tray of water. Ask your students to predict which seedlings will grow tallest, those in the light or those in the dark?

2. Wait until your window seedlings are 4-6 inches tall. Then remove your dark grown seedlings. Have them measure the height of both sets of seedlings and compare the difference. Which are tallest? (Dark grown seedlings should win easily.) What makes the dark grown seedlings taller? (Stem elongates more between points of leaf attachment.)

3. How do the seedlings differ in color? (Dark grown seedlings are a creamy white color and should show no evidence of green chlorophyll.) What is required for plants to make chlorophyll? (light)

4. Why is it important for seedlings to act this way? (Seedlings must elongate until they get to the light. They don't know how deep in the soil they may be. So they elongate until they run out of stored food.) What stops them from continuing this rapid elongation? (light)

5. What happens to the seedlings by the window? (They turn toward the light.) How fast do they bend? (This can be

LESSON 5 Continued

determined by turning the pots and seeing how fast they straighten and bend the other way. This is a demonstration of a positive phototropism.) What would happen if the seedlings were germinated with only a light shining on them from the side? (They would bend toward the light, which is called a positive phototropism.) So roots show a positive geotropism and shoots show both a negative geotropism and a positive phototropism.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 6 WHAT SEEDS ARE AROUND THE HOUSE?

Background Information

Seeds are used around the house for many things, but the three primary uses are for food, for flavorings, and for flower and vegetable gardens.

Materials paper glue patient parents peat pots soda bottle greenhouses

Procedure

1. Have your students make a collection of all the various kinds of seeds they can find in their house. Samples can be glued to construction paper, and labeled to indicate what the seed is and what it is used for.

2. More advanced students might be asked to group the seeds into categories of similar types. Or they might look them up in an encyclopedia to find out where they come from or where they are grown.

3. How many of these seeds will grow? Use peat pots and soda bottles to find out how many of their seeds from around the house will grow. Seed viability is limited, so very old spices will probably not germinate. Large tropical seeds like nutmeg and star anise will never germinate, they must almost be tree fresh to grow, so you might as well not try. Lots of the others will grow quite well (see Appendix A).

4. Do the seedlings show a pair of cotyledons when they come up? (Most of your household/garden seeds will, a few won't.) How do they differ in shape and size? Can a good gardener tell what is coming up? (Yes, most have pretty characteristic shapes and sizes.) Which come up the fastest and which are the slowest? (mustard, radish, lettuce are fast at 3-5 days under good conditions; dill, celery and others can be pretty slow at 10-14 days). Make a chart to record new germinations and post them on a wall.

(What, no good windows in your classroom?! A set of fluorescent shop lights will solve the problem. However, the lights must be suspended just a few inches above the plants, and they should be adjustable to allow for growth. If you're really handy, you could make a light-weight wooden frame to fit over a tray. Staple plastic to your frame and you've got a dandy little greenhouse.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 7 FLESHY FRUITS AND SEEDS

Background Information

The seeds of flowering plants are contained within fruits, which function to protect and/or disperse the seed or seeds within. The ovary portion of a flower's pistil will mature into a fruit, while the ovules within will mature into a seed or seeds. Fruits can be fleshy or dry. Fleshy fruits generally are designed to attract animals, which disperse the seeds while eating the fruits. If swallowed, these seeds can pass through an animal's gut unharmed. When immature, many fleshy fruits are hard and sour and serve to protect the developing seeds within. When they ripen, fleshy fruits develop an attractive color and odor, and the flesh softens. Since we are animals, we find many fleshy fruits appealing, but they vary greatly in internal organization and number of seeds.

Materials waxed paper or paper plates (work surface) sturdy plastic knives variety of fleshy fruits: cherry tomatoes, plum/peach/cherry, apple/pear, grapes (not seedless), cucumber, squash/gourd/melon, lemon/lime/orange (not navel), watermelon fruits grouped together will show essentially the same organization, so one representative will be plenty

Procedure

1. Ask students to investigate these fruits to determine:

a. How many seeds does each one contain? (1-10, many) b. Where are the seeds located? c. How many parts, segments, or divisions make up the fruit? d. What part of the fruit is edible? e. Is there a thin or thick skin? Is there a stony pit or core? Is there a hard rind and fleshy center?

2. The best approach is to start by making longitudinal section, and then making a cross section of one half. From these two views you can answer the questions in #1.

3. Make a chart which records their results. List fruits on one side, and list the data obtained by each group in columns.

4. Have students make diagrams to show where seeds are found. Discussions can follow to compare and contrast results. They should grasp the concept that fruits are associated with seeds.

Continued

LESSON 7 Extensions/Variations

DRUPES 3-layered, 1-seeded fruits (plum/peach/cherry). Note the pit is part of the fruit (an inner stony layer), which has to be cracked open to find the seed (almonds are the same fruit type, but the outer fruit has already been discarded). This type of fruit has a thin skin, a fleshy middle layer, and a stony inner layer containing 1 seed (stone fruits).

POMES Fleshy fruits with a many-seeded, five-parted central core (apple, pear).

BERRY Fleshy fruit throughout, many seeds embedded in flesh (grape 3-4 seeds, tomato, kiwi, cucumber).

PEPO Firm or hard skin and outer layer surrounding fleshy or fibrous, many-seeded inner layer (cucumber, squash, melons). The pepo fruit type can be similar to some berries. Cucumbers show 3 distinct segments in cross section.

CITRUS or HESPERIDIUM Thick skin or rind surrounding many-seeded fleshy layer in many distinct segments (lemon, orange, etc.). Latter name comes from Greek mythology (golden apples in garden of Hesperides).

BERRIES THAT AREN'T BERRIES (strawberry, raspberry, blackberry, mulberry). Raspberries and blackberries are made up of many drupe-like fruitlets because their flowers have many pistils. Strawberries are similar except the stem beneath the dry achene-like fruits (see Dry Fruit Types below) enlarges and become fleshy. A mulberry, also pineapple, are many separate fruits fused together.

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 8 WHY DO FRUITS HAVE SKINS?

Background Information

Most fleshy fruits have a discrete skin. Some even have a thicker, harder portion of the fruit wall, a rind, which surrounds softer, fleshier tissues within. Many of the smooth skinned fruits also have a waxy cuticle covering the skin. Their general function is to prevent water loss.

Materials scale or balance several smooth-skinned fruits--at least 3 of each (apple, cucumber, orange) potato peeler waxed paper spray cleaner

Procedure

1. Weigh one unaltered fruit (your control). Peel and then weigh another fruit (your 1st experimental treatment). Use the spray cleaner to thoroughly wipe clean the skin of another fruit (your 2nd experimental treatment). Record the data for each in a data table for "Day 1".

2. Weigh each daily for several days. Continue filling in the data table for "Day 2", "Day 3", etc.

3. At the end of the experiment, allow students to draw conclusions about the function of the skin and the waxy cuticle. Ask about other changes that do not necessarily relate to drying out, for example, changes in color. How does the flesh inside the control fruits look? What seems to happen when exposed to the air?

4. Do fruits with intact skins, i.e., your controls, lose water too? If so at what rate? To determine this, you may wish to continue weighing the controls for a longer period of time. How many days would it take a fruit with a skin to dry out as much as a peeled fruit after say 5 days? Can you calculate this? How much does the waxy cuticle contribute to reducing weight loss?

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

LESSON 9 VARIATION IN DRY FRUITS

Background Information

Dry fruits are similar to fleshy fruits, except the ovary matures into a dry or hard stony fruit wall. Most dry fruits have fewer seeds than fleshy fruits, but they are better protected and do not have to make the perilous journey through a gut. Note: among fleshy fruits, 1-seeded drupes are more commonly discarded than swallowed and they're better protected. So the reproductive strategy is to either invest in lots of seeds putting little investment in protection, or invest in a large, well-protected seed.

Dry fruits can make wings, floats, hooks, or burrs to transport seeds. Hard shelled dry fruits (nuts) protect the large seed within, and frequently the seed/embryo within is very large.

Materials sunflower seeds pistachio nuts nuts peanuts in shell almonds nut cracker/hammer/brick

Preparation Many other fruits can be found on a short FIELD TRIP. During the fall many types of dry fruits can be found around the school yard, nearby sidewalks, alleyways, and hedgerows. What can they find? Offer a prize to the most careful observers. Provided below is a list of the most common and easily identified dry fruit types. Dry fruits can be saved and your class may want to start a collection.

Procedure

1. Dry fruit types can be investigated similarly to fleshy ones, but sometimes not quite so easily. Have students take apart and investigate fruits as before.

2. Questions to answer.

a. How many seeds does a fruit contain? b. Is the fruit wall thin or thick? c. Is the fruit easy or hard to open? d. Does the fruit have any means of transport? e. Is the fruit good protection?

3. Label the fruits and decide what type of fruit it is.

Continued

LESSON 9 Variation in Dry Fruits

Dry Fruit Types

FOLLICLE One to many-seeded, splits open along 1 seam (milkweed pod, pistachio). Seeds have plumes for wind dispersal.

LEGUME One to several seeds, splits open along 2 seams (peanut, bean, pea)

CAPSULE Many small seeds, opens by cap, slits, or pores at top (poppy, snapdragon). Seeds are sprinkled out like a salt shaker and usually blown around.

ACHENE One-seeded, loose within thin shelled fruit (sunflower and all other members of aster/daisy family). Some have barbs or hooks to catch on animal's fur or your clothes (beggar-ticks).

NUT One large seed within a thick stony shell (walnuts, hickory, acorns, pecans). Acorn embryos can be examined much like that of beans. What are you eating when you eat a pecan or walnut? (Usually just 1 cotyledon.) Many nuts have a hull or outer fruit layer that can be partly fleshy. Sometimes this outer layer smells bad to discourage seed-eating animals.

SAMARA One seed in a winged fruit (maple, ash). What happens when the fruit is dropped from a height? (rotates) What kind of aircraft does this remind you of? (helicopter) What kind of plant probably makes such a fruit? (tall tree)

CEREAL GRAIN A one-seeded fruit fused into one unit (all grasses including corn, wheat, rice, oats, barley, rye). We usually refer to cereal grains as seed since we cannot physically separate the seed from the fruit. The fruit wall is called BRAN and is removed on milled grains (rice, wheat to become white flour). The embryo is called the GERM because it germinates. The rest of the seed is endosperm, a starchy tissue.

Continued

LESSON 9 Fascinating Facts

When is a nut not a nut? Peanuts are legumes or beans. Coconuts are not nuts, just very large, hard-shelled seeds. (The only seed that's larger is the double coconut!) Coconuts have 1 small, cylindrical embryo beneath one of the three eyes, and the rest of the seed is filled with liquid (coconut milk) or solid (coconut meat) endosperm, which is a nutritive tissue for the embryo's growth. Coconuts right off the palm tree are surrounded by a large, fibrous, drupe-like dry fruit that can float for weeks.

FRUITS, SEEDS, AND PLANT REPRODUCTION

APPENDIX A SEEDS AROUND THE HOUSE

Here's the list of seeds I found at my house. I've indicated which should grow (y), and which probably will not (n). A question mark means probably, but I'm uncertain. Their general use is also given, although it should be obvious enough. A short field trip might yield a number of fruits and seeds (acorns, walnuts, sunflower, milkweed, sticktights, burrs, etc.).

Allspice (n) spice* Nutmeg (n) spice Dill (y) herb* Caraway (y) herb Szechuan Pepper (y?) spice Celery seed (y) herb Poppy seed (n) herb Fennel (y) herb Coriander (y) herb Cardamom (n) spice Alfalfa (y) food (sprouts) Mung beans (y) food (sprouts) Radish (y) garden** Lettuce (y) garden** Cucumber (y) garden** Okra (y) garden** Peas (y) garden (Pink seeds are treated) Basil (y) garden, herb** Parsley (y) garden, herb** Carrots (y) garden** Spinach (y) garden** Sweet corn (y) garden** (only eaten when immature) Cabbage (y) garden** Sesame seed (y) herb Star Anise (n) spice Fenugreek (y) herb Mustard seed (y) herb Cumin (y) herb Black Pepper (n) spice Coffee bean (n) beverage Popcorn (y) food Beans, many kinds (y) food Various Flowers (y) decoration Rice (n, it's milled so embryo is removed) food Peanuts (n, they're roasted) food Squash, several kinds (y) garden** Lentils (y) food ___________________________ * There is no specific difference between "spice" and "herb." Herbs in this list are aromatic seeds (and leaves, but they won't be listed here) of European or Middle Eastern origin. Spices are aromatic seeds (and other plant parts) of exotic, tropical origin. ** Seeds indicated as "garden" aren't eaten directly as food, but are planted to raise something edible. Some, e.g., peas, could go both ways.

FRUITS, SEEDS, AND PLANT REPRODUCTION

APPENDIX B BOTANICAL/SCIENCE LITERATURE FOR ELEMENTARY GRADES

DeBruin, J. 1980. Creative, Hands-On Science Experiences Using Free and Inexpensive Materials. Good Apple, Carthage, IL.

Heller, R. 1984. The Reason for a Flower. Grosset and Dunlap.

Hillen, J. and E. Hoover. 1990. Primarily Plants. AIMS Educational Foundation, Fresno, CA.

Hone, E. B., A. Joseph, and E. Victor. 1971. A Source Book for Elementary Sciences. Harcourt Brace Jovonovich, NY.

Jaffe, R. and G. Appel. 1990. The Growing Classroom: Garden Based Science. Addison Wesley, NY.

Kuchalla, S. 1982. All About Seeds. Troll Associates.

Kuslan, L. I. & A. H. Stone. 1968. Teaching Children Sciences: an Inquiry Approach. Wadsworth, Belmont, CA.

Selsam, M. E. 1959. Seeds and More Seeds. Harper and Row.

Shuttlesworth, D. E. 1976. The Hidden Magic of Seeds. Rodale Press.

Wexler, J. 1987. Flowers, Fruits, and Seeds. Prentice-Hall.

FRUITS, SEEDS, PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 1 WHAT'S IN A SEED?

Materials Roasted peanut, bean (soaked in water overnight), a bean seedling (7-10 days old).

Activity 1 Carefully dissect the peanut and the bean. After removing the seed coat, diagram what you find within the seed in the spaces below.

Bean___________ Peanut___________

Do both seeds have the same parts? How are they different? How are they the same? ______________________________________________________________________

______________________________________________________________________

Activity 2 Compare the contents of the two seeds with a bean seedling. Try to find all of the same seed parts on the seedling and use your observations to decide which parts have the following functions. Label your diagrams with letters based on your decisions.

Part A. Forms the leafy shoot__________________________________

Part B Stores food for growth_________________________________

From the following description fill in the blanks above. Bean and peanut seeds are completely filled by an immature plant, an embryo (m-bree-oh). In the bean and peanut, the embryo consists of an embryonic leaves, the cotyledons (cot-e-lee-dons). The cotyledons store food for early growth of the seedling. The shoot will consist of a folded pair of true leaves, which are heart-shaped. The root ends in a growing point, a meristem (mer-eh-stem)

What happens to the cotyledons as the seed germinates and grows?

______________________________________________________________________

FRUITS, SEEDS, AND PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 2 HOW DO SEEDS GROW?

Observe your germinating seeds carefully each day. To record changes draw a seed each day. Label Day 1, Day 2, and so on. Use your observations to answer the following questions.

SUBJECT________________________________________________(name of plant)

1. What part of a seed appears first? ______________________________

2. Does the root branch? ___________________________________________

3. What part of the embryo appears above ground first? ______________________________________________________________________

4. Compare your answer to #3 with that of other students studying another type of seed. Do all plant seeds grow the same way? If no, how many different ways of growing did you discover? List them below. ______________________________________________________________________

______________________________________________________________________

5. What part of the seed is the embryo in corn? Does the embryo fill the whole seed like the bean? Hint: Where do the root and shoot emerge from the seed? ______________________________________________________________________

______________________________________________________________________

6. Which seedlings have cotyledons that are the most like regular leaves? List the plants below. ______________________________________________________________________

______________________________________________________________________

7. Suppose someone planted your garden, but forgot to label what was planted in each row. Could you tell what kind of seed was planted as soon as the seedling appears? Can gardeners learn to identify weed seedlings from flower or vegetable seedlings? How? ______________________________________________________________________

______________________________________________________________________

FRUITS, SEEDS, AND PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 3 HOW DO SEEDLINGS BREAK OUT OF THEIR SEEDS AND PUSH THROUGH THE SOIL?

Activity 1 Compare a dry bean to a soaked bean. Measure their lengths and widths. You have already compared their weights in the previous lesson. What happens to a seed just before it begins to grow? What has happened to the seed coat? ______________________________________________________________________

______________________________________________________________________

Activity 2 How strong is a seed? Could a few seeds lift a brick? What would happen if you put a brick on top of 4 or 5 dry beans, and then allowed the beans to soak up water? Weigh the dry beans and then weigh the brick. When the brick is on the dry beans measure how high the brick is above the surface the beans are sitting upon. After they have absorbed water overnight, measure the height of the brick again. Did they lift the brick? How many times their own weight did the beans lift? ______________________________________________________________________

______________________________________________________________________

Weight of beans_________________ Weight of brick_______________

Height of brick before soaking beans______________

Height of brick after soaking beans_______________

Number of beans used_______________

A germinating bean can lift _________ times its own weight.

Activity 3 Now use this information to predict what will happen in the following situation: You fill a small gar with beans or peas. After making some holes in the lid to allow water in, you screw the lid on tightly. Then you place the jar into a larger jar or pail of water. What might happen? ______________________________________________________________________

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Continued

WORKSHEET LESSON 3 Continued

With the help of your teacher, try the demonstration and find out what really happens. Do you think the same thing will happen all the time? ______________________________________________________________________

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Activity 4 Thinking Now, just like a scientist, think of a hypothesis (high-poth-eh-sis) (an idea that explains how something happens or works) that would explain how a seed breaks out of its tight seed coat or a hard fruit (like a nut), and how it manages to push through hard soil.

HYPOTHESIS____________________________________________________________

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FRUITS, SEEDS, AND PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 4 DO SEEDS KNOW WHICH WAY IS UP?

Observation 1 Take 4 seeds of bean and 4 seeds of corn that have been soaked in water overnight and examine them carefully. Notice that they have markings and differences in shape. Arrange the four seeds so that they point to 12, 3, 6, and 9 o'clock. Draw how you have them arranged below.

CORN

12 o'clock 3 o'clock 6 o'clock 9 o'clock

BEAN

12 o'clock 3 o'clock 6 o'clock 9 o'clock

Observation 2 Your teacher will show you how to use paper towels and plastic cups to make a growth chamber. Put 4 seeds in each so that they point in all four directions you have shown above. Use a marker to indicate the 12, 3, 6, and 9 o'clock positions.

Over the next few days observe where the root and shoots emerge from the seeds, and which direction they grow.

Do roots know which way is down? _____________________________________

Do shoots know which way is up? ______________________________________

Time to think. What could a seed be sensing to know which way is up and down? ______________________________________________________________________

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Continued

WORKSHEET LESSON 4 Continued

Suppose you were to conduct the same experiment in the space station orbiting Earth. How would the results be different?

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Can you think of an experiment where you could show how seeds know which way is up and down? To help you, watch the demonstration your teacher will perform. When you drop a weight it goes straight down. When you swing the same weight around your head on a string, it does not fall down. You can do the same thing with a bucket of water, but be careful how you stop.

Now suppose you could do something similar to seeds just beginning to grow. Describe your experiment below and explain what you think the results will be.

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FRUITS, SEEDS, AND PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 5 HOW DO PLANTS KNOW WHEN THEY ARE ABOVE GROUND?

Question 1 Can seeds grow in the dark?

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If you don't know, why don't you find out by conducting an experiment.

Question 2 Which seeds will grow biggest and tallest? Seeds grown in the dark or in the light?

YOUR PREDICTION ______________________________________________________________________

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Testing Your Prediction

To test your prediction, plant some seeds following the instructions of your teacher. Place one set in a completely dark place and another set in the light or by the windows. In an experiment like this, we compare the results of two different situations, one called the TREATMENT (the dark) and one called the CONTROL (the light). Why do you need both a treatment and a control to have a good experiment?

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At the end of the experiment, in 6 or 7 days, measure the heights of the two sets of seedlings.

Height of seedlings grown in the Dark ________________________________

Height of seedlings grown in the Light _______________________________

Was my prediction correct? ___________________________________________

What are the seedlings grown in the dark trying to do?

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What color are the seedlings grown in the dark? ______________________

What color are the seedlings grown in the light? _____________________

Continued

LESSON 5 WORKSHEET Continued

Do the shoots of seeds grown in the dark know which way is up? ______________________________________________________________________

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Is this the same as roots or the opposite?

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Time to think. What does light do to seedlings? Do seedling shoots know when they have reached the surface of the soil?

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What happens to seedlings left growing by the window? Do they grow nice and straight? What do the plants seem to be doing?

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FRUITS, SEEDS, AND PLANT REPRODUCTION (Student Copy)

WORKSHEET LESSON 7 FLESHY FRUITS AND SEEDS

Name of the fruit_____________________________________________________

Number of seeds in the fruit__________________________________________

Number of sections seen in the fruit__________________________________

Draw a picture to show where the seeds are located.

Use arrows to show what part of the fruit we eat.

Do we take the peel off before we eat it? ____________________________

Have you ever eaten this kind of fruit before? _______________________

FRUITS, SEEDS, AND PLANT REPRODUCTION (Teacher Copy)

WORKSHEET LESSON 8 WHY DO FRUITS HAVE SKINS?

Activity 1 Take an apple or a cucumber. Now buff to make them look shiny. What substance do you suppose makes that happen? What do you do to a car to make it prettier and shiny? What else does this stuff do? To help you answer the questions, put a drop of water on a piece of waxed paper and on a piece of regular paper. ______________________________________________________________________

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This layer is called the cuticle. How do you think the skin and cuticle work to keep a fruit fresh and juicy? ______________________________________________________________________

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Activity 2 Designing an experiment. How can you measure the amount of water in a fruit? Let's use another example. Suppose you weighed someone and then they drank 1 to 10 cups of water, but you didn't know how many. Since a cup of water weighs 1 pound, what do you need to do to find out how many cups of water they drank? Think quick before they need a rest room. ______________________________________________________________________

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Do the cuticle and skin stop the fruit from drying out, or only slow down water loss? Using a balance, figure out how to answer this question. ______________________________________________________________________

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How fast will a fruit dry out without its skin? Is there any way to do this? Do you ever help in the kitchen? ______________________________________________________________________

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Continued

WORKSHEET LESSON 8 Continued

Suppose you could remove the waxy cuticle, but leave the skin whole. Would this fruit dry out faster or not? ______________________________________________________________________

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In experiments, every time you try something different, it is called a TREATMENT. But to find out if a treatment actually causes a particular result, you also need a CONTROL--something measured or observed exactly the same way, but unaltered. What would be your treatments and control in an experiment to decide why a fruit has a skin?

CONTROL ______________________________________________________________

TREATMENT A __________________________________________________________

TREATMENT B __________________________________________________________

What are you going to record? Make a data table on the rest of this page. Suppose this experiment will run 10 days.

Continued

WORKSHEET LESSON 8 Continued

CONCLUSIONS

1. Which treatment lost weight the fastest? ______________________________________________________________________

2. Which fruit lost the least weight? ______________________________________________________________________

3. Why do fruits have a waxy skin? _____________________________________________________________________

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4. Does the waxy skin stop drying out, or just slow it down? ______________________________________________________________________

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5. Visit a market and make a list of fruits with waxy skins. ______________________________________________________________________

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6. Many vegetables (potato, carrot) have corky skins or peels. Although it seldom gets so thick, corks are made from the corky bark of an oak. These cork cells have waxy cell walls. Why do we use them as bottle stoppers? Predict what would happen to a potato once it has been peeled, and then describe an experiment to test your prediction. ______________________________________________________________________

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