Unit 2: Plant Detectives:

Lesson 2: Plant Needs, Water

Grade Level: Kindergarten

Time Required: 30 minutes

Primary AZ State Standards:

(Cross-reference “Standards Matrix” for full listing)

Science:

S00-S4C3-02: Identify that plants and animals need food, water, air, space.

S00-S4C3-03: Describe changes observed in a small system (controlled

plant experiment)

Math:

M00-S2C1-02: Ask and answer questions by counting, comparing quantities, and interpreting simply displays of data.

Objective(s):

Students will explore how water is an essential need for plants.

Students will learn that plants need just the right amount of water to thrive.

Background Information:

Water plays an important part in plant functioning, just like other living things. Water transports nutrients and energy reserves from the roots to all different parts of the plant. Just like people, plants also lose water through transpiration in order to keep cool. Furthermore, plants need water to stay erect. Without water, the plants wilt and eventually die.

In the winter, many plants allow their above-ground parts to grow dormant (go to sleep) and water circulates much more slowly throughout the plant because of freezing temperatures. However, evergreens have a much higher water need throughout the year. Without any water in the winter, many plants would die.

Lastly, there is the problem of too much of a good thing. Plants that are overwatered can also die. (Did you know that people can die from drinking too much water too? It’s called hyper-hydration!) Roots need both air and water. Too much water can cause the roots to suffocate, rot, or become more susceptible to plant diseases. In this experiment, students are going to experiment to see how much water a plant needs to survive.

Pre-lesson Preparation:

  1. Obtain 20 live plants. You might use seedlings for a veggie garden that are already several weeks to a month old. Because they are still seedlings, they will show a little more dramatic results, but they are not so young that they would keel over and die without getting water every other day. Recommended plants include tomatoes (determinate), sunflowers, or marigolds. These have a rapid growing rates and an upright growth form.

Activity Instructions:

Whole group introduction

10 minutes

  1. Check in with students on light experiment. Discuss observations and results if enough time has elapsed.
  2. Tell students, “Today, we are going to put on our detective moustaches again and get to work!” Distribute moustaches.
  3. Have students brainstorm reasons that water is important to living things. Compare to human needs (talk about dehydration and the importance of drinking in water in arid climates like Arizona).
  4. Ask students if water is a need or a want for living things.

Water experiment

(Adapted from “Water We Gonna Do?” lesson plan. Used with permission from California Foundation for Agriculture in the Classroom. See “Resource” list at end of this lesson for website link.)

Five small groups

20 minutes

  1. Put students into five groups. Assign roles to students such as:
  2. Material gatherer
  3. Setter-upper
  4. Recorder
  5. Water pourer
  6. Observer
  7. Cleaner-upper

Students can stay in roles throughout the experiment or rotate through roles. Write their roles down on the observation sheet so they don’t forget.

  1. Explain the question of the experiment. “How much water do our plants need? What is too much? What is too little? What is just right?”
  2. Ask students how they will figure out if the plants like how much water they are getting. Look at how they are growing or if they are dying. (Students are going to measure growth with a ruler.) Have students make predictions.
  3. Help students set up the experiment. Give materials to material gatherer. Each group needs:
  4. 4 plants
  5. 1 observation sheet – Appendix KE
  6. Water labels – Appendix KF
  7. 1 ruler (centimeters)
  8. A set of measuring cups
  9. A jar of water
  10. Students should cut out the labels and tape one to the front of each plant.
  11. Next, students should measure out 1 tablespoon, ¼ - ½ cup, and 1 cup of water (more or less as you see fit). Every 3-4 days, the plant labeled “a little” should get 1 tablespoon of water, the plant labeled “medium” should get ¼ - ½ cup of water, and the plant labeled “a lot” should get 1 cup. The plant labeled “none” should not get any.
  12. Have students pour in water in and measure the beginning height of the plants. Record on observation charts. You may have to review measuring and counting with students
  13. Every 3 – 4 days, students should water, measure plants, and record observations. Once the plants with no water get very wilted, you might as students to predict what would happen if they continued not to get water. You may be able to save the plants if they are intended to be planted out in your garden.
  14. Take time in subsequent lessons to discuss observations. If time allows, graph data that children collected. The experiment can be wrapped up when the plant with a lot of water starts experiencing some type of stress from too much water. This might only be apparent in lack of growth.
  15. Ask students to come up with explanations for their observations. Clarify misconceptions as needed.
  16. In closing ask students,

“Why is water important to plants?” All living things need water.

“Why should we care about how much water plants need?” So farmers and gardeners know how much water to give our plants to be healthy.

“Is getting enough water a problem in Arizona?” Yes!

“Is getting too much water a problem in Arizona?” Probably not, but it could be if you are hand-watering your garden.

Resources:

Borovoy, J. & Holtman, K. (1994). “Water we gonna do? How much water does a

plant need?”The Mysterious Plant Caper.California Foundation for Agriculture in the Classroom, Sacramento, CA. pp. 37-39.