A Third Grade Thematic Unit on the Life Cycle of Plants

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Like any other living organism, plants have a life cycle which begins with the planting of seeds and ends with the death of the plant. The proper amount of water, sunlight and soil play an important role in the growth of a plant. Each class of plant takes a different time to complete its life cycle. Some plants complete their life cycle within a year while some others live several years.

The Activity

Take your students to the garden. Provide each student with a sheet of paper with pictures of a root, flower, leaves, stems and seeds. Show them a fruit bearing plant and direct them to find the parts of the plant and mark those parts which they can identify, on the paper provided. Gently remove the soil surrounding the plant so that small roots are exposed. Pluck a fruit from the plant and show them the seeds hidden inside. Now provide each student with a plastic knife, fresh beans, an avocado and an orange. Instruct them to take out the seeds from each of the fruits and vegetables provided and record the number of seeds in each of them.


  • Pea seeds
  • Flower pots
  • Water
  • Soil


Before teaching the life cycle of plants the teacher must prepare a flower-pot and should plant the seeds. Once it is germinated take those three pots to the classroom. Divide your students into groups and provide each group with the above materials. Let each group fill the flower-pot with soil and soak the soil with water. Instruct them to plant seeds in the soil. Direct them to check the pot each day and note down their observations.

Now invite their attention to the germinated plants in the teacher’s pot. Let them identify the parts of the small saplings. Take four empty flower-pots. Number those pots and then fill three of them with soil. Gently remove the sapling from the first pot and place it in the newly prepared flower pots. Keep two of the flower pots in the sun and the third one in a dark room.

Direct your students to water the plant in the first pot, which is kept under the sun, and not to water the second pot. Take the fourth pot and fill it with papers and soak it with water. Remove another sapling and place it in the soaked paper. Keep this pot under the sun and water it too. Instruct your students to monitor the changes occurring to the plants in each of those pots. Let them continue the monitoring for one week.

Analysis and Conclusion

From their observations students will understand that the germination of a seed results in the formation of a small plant which then grows into a big flowering and fruit bearing plant. On monitoring the changes occurring to the plants in the four pots, in which each plant was kept in a different situation, students will understand that a plant will only survive if all of the conditions necessary are favorable. Those conditions are the presence of sunlight, water and soil.

Students in elementary classes like a hands-on approach in the class rather than abstract scientific facts. This 3rd grade thematic unit on the life cycle of plants provides teachers with an excellent tool to use the hands-on approach to create interest for the sciences.

This post is part of the series: Lesson plan and activities on plants

Plants and photosynthesis lesson plans, activities and ideas!!

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