The teacher leads a discussion in which students identify the physical needs of animals, and then speculate on the needs of plants. With guidance from the teacher, the students then help design an experiment that can take place in the classroom to test whether or not plants need light and water in order to grow. Sunflower seeds are planted in plastic cups, and once germinated, are exposed to different conditions. In particular, within the classroom setting it is easy to test for the effects of light versus darkness, and watered versus non-watered conditions. During exposure of the plants to these different conditions, students measure growth of the seedlings every few days using non-standard measurement. After a few weeks, they compare the growth of plants exposed to the different conditions, and make pictorial bar graphs that demonstrate these comparisons.

Determining the optimal environment for growing crops and other plants used to produce products is agricultural engineering. animals plants plant growth experimental design Students will be able to describe how a simple experiment can be conducted in order to determine if plants need light and/or water in order to grow. Begin with a brief discussion about the needs of animals, using the familiar examples of humans, dogs, and cats as examples. Students should be able to recognize that these animals all need food to eat, water to drink, and air to breath. They might also suggest that animals need clothing or shelter in order to keep warm and dry. Then ask students what they think plants need in order to live and grow. It would be helpful if there were a few house plants in the classroom that you could 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 don't 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. They should be able to determine that a garden wouldn't get as much light if it was planted in the shade of a forest, but instead, in an open area there would be lots more sunshine. Ask the students if they would like to plant some seeds and then see if their plants grow better in light or in the dark. 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 students should be well motivated to continue investigating the needs of plants. 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 try to get the student to realize that there might be a better way. Be sure to 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, i.e., placed in the light alongside the watered plants. Otherwise the class won't 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. (It is very likely that students won't really understand this idea, but it is still worth mentioning. That way it may come 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, i.e., 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 can 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. Light Plants and Dark Plants, Wet Plants and Dry Ones 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), students should be prepared for the activity part of this lesson. At this point, student assessment is not appropriate; this should occur after the activity component is completed.