SECOND GRADE - MEASURING PLANT HEIGHT OVER TIME

OBJECTIVES:
·         Comparing different plants.
·         Learning how to measure plant growth.

VOCABULARY:
·         leaves
·         plant
·         nutrients
·         habitat
·         seasons

MATERIALS:
·         plant growth models
·         ruler
·      plant model worksheet
·      plant height worksheet
·         plant growth summary
·         plant growth graph

BACKGROUND:

Plants are living organisms and share common characteristics with all other living things. All organisms are composed of cells, grow, reproduce, and respond to various kinds of stimuli like temperature. However, plants have additional characteristics which distinguish them from other organisms. Plants have the ability to manufacture food (photosynthesis); have unlimited or almost unlimited growth; and cell walls made of cellulose (used in making paper). Students should learn that most plants are green, have roots, grow, have flowers, have leaves, live in soil, and drink water.

The kingdom of plants includes seed plants, algae, ferns, and mosses. Plants have many cells and tissues. They make their own food using chlorophyll (the green pigment) through a chemical process called photosynthesis, which converts water and carbon dioxide into sugars, if there is enough light. They do not move on their own.

Children sometimes mistake some invertebrate animals, like coral or sea anemones as plants. Children reason that if it looks like a plant, it is a plant. Even mushrooms, most children think is a plant because it grows. Children that just see a part of plant like a bulb, root, or seed may not think it is a plant because it is not green.

This long term project focuses on

QUESTION:  How do seasons affect plant growth?

BACKGROUND
Students will learn that milkweed grows rapidly in fall and then growth slows in the winter.  Many plants in the fall start going dormant.  But in San Francisco Bay area weather, fall means that there is more moisture in the air, and many drought tolerant plants like milkweed actually grow well, because the monarch return in winter and this provides food for the caterpillars.

Students will measure the height of the milkweed plant over time and then plot the information.

PRIOR RESEARCH FOR CLASS:  butterflies, milkweed, plant growth

EXPERIMENTAL DESIGN:  Set up enough milkweed in 5 gallon containers so children can work in partners and have their own plant to measure. 

1.    Look at the growth models. 

Seed:  The life cycle of a plant starts with a seed. The purpose of the seed coat is primarily to protect the embryo (or baby) plant against such hazards as excessive drying, mechanical injury, and the digestive juices of animals (if it is eaten). Many seed coats are impermeable to water or oxygen or are hard which helps it remain "asleep" or dormant for a long time. When the conditions are right the dormant seed will grow or germinate. 

Remember a seeds are used by other organisms as food, because seeds have food stored in them. Seeds furnish humans with great proportions of food. A large part of the world relies on the grains of wheat, rice, soybeans, corn, rye, and barley. Oils and fats are produced from the seeds of coconut, corn, cotton, flax, castor bean, sesame, peanut, and soybean. Oil from the cotton seed and peanut is utilized in the manufacture of various products such as butter and lard substitutes and soap.

Sprout + root: Roots help anchor the plant to a substrate and draw water and minerals from the soil. Some roots form a shallow network underneath the soil surface, while others have tap roots that can go quite far down to find water and anchor the plant. 

A root will go into the earth while the leaves go toward the light.  The sprout grows toward the light because it needs light to develop a system to get food (or energy) from the sun  (photosynthesis).  The sprout is developing nutrients from the soil (especially nitrogen) to create chlorophyll which will help the plant make food for itself.

Roots + leaves: Most of the food produced by plants is made in the leaves. The leaves provide ample surface area for the absorption of light energy and contain many chloroplasts (which contain the molecules of chlorophyll)  and it is in the chloroplasts where photosynthesis occurs.

Chlorophyll has pigments that take in energy from the sun and convert carbon dioxide and water into sugars, which is called photosynthesis.  Photosynthesis allows the plant to feed itself and continue to grow. 

Stem + leaves + roots:  The last model shows the difference growth that children will be measuring.  Notice that there is height, width, and depth.  Also the leaves will start to branch.  All of this growth needs to be captured by the students in their data collection.

2.    Assign a pot to 2 students and have them measure length and width.  Collect the data on the “data sheets.”   Eventually you will need to plot the data on a line graph.  But this can be done once you have collected enough data so the students can do it as a class activity.  Remember each plant has its own sheet and graph.   If you know how to use an Excel Spreadsheet you can put it on one graph to compare.   But not necessary for the children to learn how to collect and plot data.

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