Lesson Let’s Plan an Experiment:
What Do Plants Need?

Learning Objectives

After this lesson, students should be able to:

• Discuss what plants and animals need to survive.
• Describe how a simple experiment can be conducted in order to determine whether or not plants need light and/or water in order to grow.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Introduction/Motivation

Begin with a brief discussion about the needs of animals, using the familiar examples of humans, dogs and cats. Expect students to be able to recognize that these animals all need food to eat, water to drink and air to breathe. They might also suggest that animals need clothing and shelter in order to keep warm and dry.

Then ask students what they think plants need in order to live and grow. It is helpful to have a few house plants in the classroom to refer to. Perhaps students have seen you water them, or if houseplants are not available, perhaps they have seen lawns and gardens being watered. If students do not suggest light as a need of plants, simply ask them if they think plants need light. You could help them reason out the answer by asking if gardens and farms are planted in forests or in open areas. Expect them to make the connection that gardens would not get as much light if they were planted in the shade of a forest, but instead, in an open area with lots more sunshine.

Ask students if they would like to plant some seeds and then see if their plants grow better in light or in the dark (Refer to the associated activity Light Plants and Dark Plants, Wet Plants and Dry Ones for more information). Point out that they can also find out if their plants need water or not. Since young children generally enjoy growing plants from seeds, and will monitor their progress with enthusiasm, at this point expect them to be well motivated to continue investigating the needs of plants.

Lesson Background and Concepts for Teachers

Body of Lesson:

Announce that you have materials so that each student can grow some plants from seeds. Then point out that this provides as opportunity to do an experiment to determine if plants really do need water or light. Ask for ideas as to how this could be done. Be sure to listen to all ideas, and without directly stating that an idea or some aspect of it won't work; instead, ask leading questions to get the student to realize that a better way might exist.

Point out that if the class wants to see if water is necessary, it is important that the non-watered plants be otherwise treated just the same as the watered ones, that is, placed in the light alongside the watered plants. Otherwise the class will not be able to tell if it was the lack of water that was responsible for any differences that occurred, or if it was some other difference in the plants' locations that was responsible. (Students may not understand this idea, but it is worth mentioning with the hope that it comes to memory when students are asked to conduct other experiments in the future.) Likewise, if the class wants to find out if plants will grow in darkness, explain that they, too, must otherwise be treated the same as the plants grown in the light, that is, they should be watered just like those grown in the light.

Try to let students come up with a way to keep some of the plants in the dark by asking for suggestions. The more input they have into the design of the experiment, the better. A dark closet or cabinet is ideal, or a space can be created from a large cardboard box draped in black felt.

Associated Activities

• Light Plants and Dark Plants, Wet Plants and Dry Ones - Students plant sunflower seeds in plastic cups, and once germinated, expose them to different conditions of light levels and/or soil moisture.

Lesson Closure

Once the basic questions of what the experiment (or experiments) will be about, and how the room can be used to conduct the experiment(s), have students prepare to conduct the associated activity.

Assessment

Patterns: Have students use their observations to describe patterns of what plants need to survive.

Perform student assessment after completion of the associated activity.

Copyright

Contributors

Supporting Program

Acknowledgements

This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.