What Can We Learn About Plants at the Pond? - Seed Sense

Corroboree 4-H Across the Seas

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OREGON BENCHMARKS

Benchmark 1

Recognize Characteristics that are similar and different between organisms.
Describe how related plants have
similar characteristics.

Benchmark 2

Group or classify organisms based on a variety of characteristics.
Describe basic plant structures and their functions.
Describe the life cycle of an organism.

USA NATIONAL SCIENCE EDUCATION CONTENT STANDARDS

Grades K-4

Systems, order, and function.
Form and function.
Characteristics of organisms.
Life cycles of organisms.
Understanding about scientific inquiry.

Systems, order, and organization.
Form and function.
Structure and function of living systems
Understanding about scientific inquiry

VICTORIAN LEARNING OUTCOMES

Biological Science:

3.1 Describe environmental factors that affect the survival of living things.

4.2 Describe how selected systems of plants and animals function.

CONTENT OBJECTIVES

Learners will be able to do the following:

Observe seeds and notice their distinctive features.
Design a classification system for seeds to distinguish between
monocots and dicots.
Identify similarities and differences between monocots and dicots.

PROCESS OBJECTIVES

Learners will be able to do the following:

Make observations.

What Can We Learn About Plants at the Pond?

Lesson A - Seed Sense

FYI

There are nine divisions (called phyla in other kingdoms) in the plant kingdom. These are mosses and liverworts (Bryophyta); club mosses (Lycophyta); ferns (Pterophyta); horsetails (Sphenophyta); gnetums (Gnetophyta); ginkgo (Ginkgophyta); cycads (Cycadophyta); conifers (Coniferophyta); and angiosperms, sometimes called “flowering plants” (Anthophyta).

When a flowering plant or angiosperm is done flowering, it forms a seed that generally is protected by a fruit. The cotyledon is the part of the seed that stores food. This food supply supports a young plant’s growth until its leaves can produce its own food. This cycle of plant to flower to seed to new plant sometimes is called the seed cycle.

There are two types of cotyledons: the monocotyledons (“monocots”) and the dicotyledons (“dicots”). Monocots have one cotyledon. Rice and corn are monocots. Dicots have two cotyledons. Lentils, lima beans, and green beans are dicots.

The epicotyl is the structure inside the seed from which the first true leaves will form. You may wish to get some peanuts, open them, and show the parts on the inside of a seed. Young children sometimes learn to call this structure in the peanut the “gnome” or “Santa Claus.” Caution: Before you use peanuts in an activity, be sure that no one in the group is allergic to them.

The hypocotyl is the area of the seed that forms the lower stem and roots. The epicotyl is above the hypocotyl; the radicle is below it.

The radicle is on the lower tip of the hypocotyl. It is the area that develops into the main root system.

Parts of a Bean

MATERIALS

Part 1 and Part 3

Dry corn and green bean seeds sold for gardening, one of each for each team
Dry brown rice, lentil and lima bean seeds, one of each for each team
Hand magnifying lens
Paper and pencil

Part 2

Corn and green bean seeds soaked in shallow water or wet paper towels for 4 days, one of each for each team

Part 4

For older learners only (or use as a demonstration with younger learners)

Corn and green bean seeds soaked in water 48 hours, one of each for each team
Cornstarch
Iodine
Eye dropper
Protective gloves for persons who may come in contact with iodine
Petri dishes or plates
Preparation
Buy seeds that have not been treated with fungicide or other chemicals. Sprout the seeds as described above for parts 2 and 4.
There should be three sets of seeds for each team:
- Set 1—corn, green bean, brown rice, lentil, lima bean
- Set 2—corn and green bean (Part 2)
- Set 3—corn and green bean (Part 4)

Procedure

Part 1

Pass out the dry brown rice, lentil, corn, lima bean, and green bean seeds (Set 1) to each team. Caution learners not to eat any of the seeds they will be working with today. Tell the teams that they will work together to classify the seeds into groups. Ask the learners to list some physical characteristics of the seeds they think might help them classify the seeds.

Now ask each team to design their own set of criteria to classify the seeds into separate groups. A set of criteria for classification is sometimes called a dichotomous key. There are two criteria listed at each step in the key (see example below: A Key to Seeds, 1A and 1B). Scientists use dichotomous keys to classify organisms. The following example is one way to design a key to the seeds in this study. Remember, this is only one example; there is more than one “right” design.


A Key to Seeds

1A:	Seeds are kidney shape		= go to 2A
1B:	Seeds are not kidney shape		= go to 3A
	2A:	Seeds are 3⁄4 inch or larger in size	= lima beans
	2B:	Seeds are smaller than 3⁄4 inch	= green beans
3A:	Seeds are round		= lentils
3B:	Seeds are not round		= go to 4A
	4A:	Seeds are long and skinny	= brown rice
	4B:	Seeds are triangle shape	= corn

Ask each team to write down their key clearly on a piece of paper. After all the teams have finished developing their key, have them trade keys. Now ask the teams to use this other team’s key to try to classify the seeds successfully.

Part 2

Ask learners to set the dry seeds aside. They will use them again later. Pass out the seeds that have been soaking for 4 days (Set 2). If the conditions have been right for growth, these seeds have germinated. The corn and bean seeds should have visible roots and leaves beginning to grow out of them. Ask learners to observe and compare the new leaves and roots of the bean and the corn. How are they similar and different? What do they see in these growing seeds that might add to the information in the key they developed in Part 1?

Ask learners to use a fingernail carefully to separate the two halves of the bean seed. Have them use the hand lens and note how the tiny plant parts are attached to the cotyledon. Ask older learners to draw a picture of the bean and label its parts. How are the bean leaf and root starts different from the corn leaf and root starts? How many cotyledons does the corn seed have? Ask older learners to draw a picture of the corn seed and label its parts.

Lead a discussion based on the information in the “FYI” section about monocot and dicot plants and the names of the parts of the seeds. Adapt the information to the age and interests of the learners.

Part 3

Ask learners to look again at the dry seeds in Set 1. What are the characteristics of monocots and dicots we identified in the Set 2 seeds? Which of the dry seeds are monocots and which are dicots? Ask the teams to separate the seeds into two groups and share their reasons.

Now learners are prepared to make a trip to the pond to look at plants and collect seeds (if available). Older learners should developa data sheet to record their observations. Which plants in and around the pond are monocots or dicots? It is not necessary for learners to know the common names of the plants in order to separate them into the two groups.

Part 4—For older learners only!

(This also may be done as a demonstration for younger learners. Because iodine is toxic, young learners should not use it. For more information, consult the proper Material Safety Data Sheet.)

Lead a discussion about the things plants need to survive. All plants need water, nutrients, and air. So far our seeds have had air and water. Where are they getting the energy or nutrients to fuel their growth? Record the answers provided by the learners. Older learners may record their ideas on the paper where they drew pictures of their corn and bean seeds.

Learners might know that plants make their food through photosynthesis. In Unit 1, we learned that photosynthesis is the process plants use to change light to chemical energy, which they use to create food (carbohydrate) from carbon dioxide and water. Many plants store the carbohydrate starch in their seeds.

Iodine can be used as an indicator for starch. When the redbrown iodine contacts starch, it becomes blue-black. Demonstrate this using some cornstarch mixed with a little water. Ask learners, “From which plant do we get cornstarch?”

Pass out the corn and green bean seeds that have soaked in water 48 hours (Set 3). Each separate seed should be on a Petri dish or plate to protect the table surface. Ask learners to mush or split open each seed, exposing the contents of the cotyledon. Explain that you will be putting a drop of iodine on each seed’s cotyledon. Caution learners not to touch the iodine with bare hands.

What do learners expect will happen? Do they expect the corn and bean to be different? Have older learners write down their predictions and then record the actual results after the iodine has been placed on the cotyledons. If learners have access to a microscope, have them look at the iodine reaction for starch in the cotyledon under the microscope.

Extend the learning

A Palette of Fun (4-H 713L): Painting with paper and milk (add seeds to the design)

If learners can plant a vegetable garden, they might try growing “the three sisters”: corn, beans, and squash. These companion plants grow well together because they offer one another mutual benefits. The corn provides living stakes for the beans. The beans are legumes, which supply nitrogen to the soil. The squash grows in the open spaces between the corn hills and provides ground cover to reduce moisture loss. Learners can study all these factors in their Three Sisters Garden.

Kidney beans or black beans and corn are significant food sources in many cultures. Learners can do research to study why these plants have been important to people living in Central and North America in the past and today. If seeds for kidney or black beans cannot be found at the garden store, those sold dry from the grocery store often will germinate.