Take the students on a field trip to a nearby pond during a spring month. Give the children time to search for frog eggs. The eggs are very recognizable because they resemble an eyeball. They are small clear/white circles with little black dots in the center.
Scoop up a batch of the frog eggs and place them in a bucket filled with the pond water. Take them back to the classroom and transfer them into a small aquarium. Hand out a small notebook to each child, and have him draw a picture of the tadpole egg inside the notebook. You may also require the students to describe where the eggs were found, and what they look like.
Draw a picture of a tadpole on the blackboard or show the children a picture of a tadpole. Then, instruct the children to check the aquarium each day to see whether the eggs have hatched into tadpoles. This can happen in as little as one week. Once the change occurs, have the children draw a picture of the tadpole on the next page in their notebooks. You may also want the children to record how long it took for the eggs to hatch and describe what the new tadpoles look like.
Explain to the children that tadpoles have the water they need to grow, but no food. Once each day, assign a student to feed the tadpoles with tadpole food. Assign two other students to change 1/4 of the tadpoles water each week. You will have to go back to the pond to obtain fresh pond water, or you can begin using spring water.
Teach the children that the tadpoles will now start to grow arms and legs. As this happens, the tadpoles tails will get smaller and smaller. Every four or five days, have the students draw and record the tadpole's changes in their notebooks.
Get students ready for the final stage of the frog's life cycle by having them recreate the changes that have already take place with a lump of clay. Children will love creating each stage of the frog's life out of the clay. This is a good visual reminder of what the students have learned. Since most children already know what a frog looks like, you can have them end the activity with a sculpture of a frog.
Release the frog back at the pond where you found the eggs, once the children have gotten to see the frog go through its life cycle. The entire life cycle can take as little as one month to complete or as long as two months.
Instruct the students to add a page to their notebooks on the adult frog. You may also give the children time to record any other thoughts or insights they had about how a frog starts off as an egg, changes in to a tadpole and eventually turns into a frog.