Matter Cycles

Upper Elementary

Screen Shot 2015-11-06 at 5.53.33 PM

Scenario: Jayla and Shaun were helping Mr. Rodriguez pack up his classroom for spring break. Shaun asked Mr. Rodriguez if someone needed to take home the class terrarium. Mr. Rodriguez reminded Shaun that the terrarium would be fine without anyone around.

Prompt: Give a scientific explanation stating what non-living parts of this terrarium ecosystem help it sustain life. Also explain why these non-living parts do not run out in this closed system.


Sample Claim: Water, air, sunlight, and soil help to sustain life in the closed system of the terrarium, and they never run out because they are recycled.


Sample Evidence: The number of worms stayed at around 12 through all 3 years without adding air, water or soil. The amount of pill bugs stayed at around 8 throughout the 3 years without adding air, water, or soil. The amount of plants stayed at around 21 over the 3 years without adding air, water, or soil.


Sample Reasoning: Water is recycled in the closed system. Plants need water to grow, and animals need water to survive. The air composition remains unchanged. The amount of carbon dioxide taken by the plants is replenished by the animals, and the oxygen needed by the animals is provided by the plants. In a closed environment, they depend on each other for survival. Decomposers play a pivotal role in replenishing the nutrients in the soil. To make life sustainable, the Sun is absolutely necessary for plants to make their own food.


Print Version


Writing a Scientific Explanation Rubric Key for Teacher