Indiana Grade 3 Science

Use plant evidence to distinguish environment from inherited differences

Compare an invented seedling record, evaluate a water-related explanation, and plan evidence that separates environment from other influences.

The Indiana science standards directory links grade-specific documents for the 2023 Indiana Academic Standards. Use the 2023 Indiana Academic Standards: Grade 3 Science for the selected performance expectation and its complete supporting information. This activity selects a Grade 3 expectation. It is one part of a science course, not a complete curriculum.

Does a shorter plant prove it inherited a shorter height?

A teacher presents an invented record for two groups of seedlings of the same plant variety. Their starting heights are similar, and the record states that they receive comparable light, soil, containers, and growing time. Group A has sufficient water; Group B has insufficient water during the recorded period. Students compare final average heights and evaluate the suggestion that an environmental difference influenced growth. No children are asked to deprive a living plant of water to produce this record.

Explain the evidence or model

Group A’s average height changes from 4 centimeters to 11 centimeters, while Group B’s changes from 4 centimeters to 6 centimeters. The groups’ average increases are 7 and 2 centimeters. The pattern is consistent with insufficient water limiting growth under the stated conditions. It does not justify saying the shorter seedlings must have inherited a shorter height: the record includes a difference in their environment. Equally, the same variety does not mean every seedling is genetically identical. Use a cautious explanation connecting the water condition with the observed growth, and identify what the invented comparison assumes rather than treating its values as actual research.

What to check in the explanation

Final height and growth are different measurements; subtract the starting height when comparing change. The values are group averages, so they do not reveal how every individual seedling grew. Averages can hide variation, missing plants, or an unusual measurement. Ask how height was measured and whether group size stayed the same. One comparison cannot establish that water is the only influence on plant height, nor that inheritance is irrelevant. Light, temperature, disease, and inherited variation can also matter. The expectation concerns traits influenced by environment; it does not require students to choose environment or inheritance as the sole explanation for every characteristic.

Plan the next activity

1. Identify the environmental difference and the conditions stated as comparable.
2. Compare starting height, final height, and change for each group.
3. Support a limited explanation and name evidence needed to strengthen it.

Plan a teacher-approved comparison using existing observations or plants receiving appropriate care. Decide how repeated individual heights, watering records, and other growing conditions would be recorded. More observations can reveal whether the pattern is consistent or depends on one unusual plant. Discuss another characteristic affected by an organism’s experiences, using an age-appropriate source rather than guessing about a person’s health or family. Many characteristics reflect both inheritance and environment. A thoughtful student response explains why the presented environmental evidence matters while leaving room for influences that were not measured.