Water and Plants...How Dry I Am

Summary

Two similar plants are observed as one gets regular water and the other does not.

Materials

For the Teacher:

• 2 plants of the same size, variety, and in the same type pot. (Coleus or begonias can be easily obtained and react fairly quickly. Also consider using plant cuttings or spider plant "babies." These would simply be placed in water or not in water.)
• Chart paper

For the Student: (Individual)

• Drawing paper
• Pencil or crayons

Background for Teachers

No known organisms can exist without access to water in some form. Water is perhaps the most important substance to life on earth. Humans, other animals, and plants need water. Water makes up about 65 of the human body. Without it, we would be able to live less than a week. Plants get water through rainfall, irrigation, and dew. Even in deserts, plants would die without moisture.

Intended Learning Outcomes

1. Make observations. 7. Distinguish between observations and inferences.

Instructional Procedures

1. Tell the students, "We are going to observe these plants for a week and keep track of what we see." Discuss the difference between observations and inferences. Observations are something you can see. Inferences are predictions. Sometimes inferences can be tested (we call these hypotheses); other times they cannot. Write observations and inferences on chart paper and put stars next to the observations.

2. Put both plants in a well-lit place where they are easily observed. 3. Water one plant every other day for 2 weeks. Do not water the other plant.

4. Ask the students to predict what they think will happen to the plants. (When a plant gets no water, it cannot make food. Without food the plant will die.) Record these predictions on a chart.

5. Draw a picture of the two plants at the end of the week. Refer the class back to the charts that have been made. "Do our observations still hold true? Can we make any judgments now about our predictions?" Discuss predictions and the evidence provided in this activity.

6. Establish the fact that plants need water to live. This would lead into a study of plant parts, particularly roots.

Extensions

1. Roots take up water from the soil. This can be shown with a potato. Peel the bottom half of a potato and slice a little off the end so that it can stand on end. Dig a hole in the top of the potato. Stand the potato on its flat end in a dish of water. The potato will soak up water from its base and fill the hole in the top with water.
2. Leave a potato in a dark, warm spot for several weeks. Ask, "What will happen to the potato? If we leave it in the dark for several months, will the potato die?" Try the experiment.
3. Have students read about how plants and animals get water in the desert.