Based on these observations, a student wrote an incomplete argument:
Claim: Gravity pulls objects toward Earth.
Evidence: When I let go of my water bottle, it fell to the floor.
Which reasoning best connects the evidence to the claim?
- Reasoning: The water bottle fell because it is made of plastic, and plastic sinks.
- Reasoning: The water bottle fell because the floor was lower than the desk.
- Reasoning: Because the bottle moved downward as soon as it was released, this shows a force pulled it toward Earth. (correct answer)
- Reasoning: The bottle fell, so the bottle fell, and that is the reason it fell.
Explanation: This question tests 5th graders' ability to construct simple arguments explaining how gravity affects objects near Earth (NGSS 5-PS2-1), specifically completing incomplete argument by providing missing reasoning component. The reasoning component is often missing in student arguments - they may provide claim and evidence but forget to explain the connection. For this question, students need to complete argument by adding reasoning that explains how evidence (water bottle fell) supports claim (gravity pulls objects toward Earth). Choice C is correct because it provides reasoning that genuinely connects given evidence to given claim using causal language ('Because the bottle moved downward as soon as it was released, this shows a force pulled it toward Earth'). This shows the student understands reasoning must explicitly connect evidence to claim using logical explanation. Choice D represents a common error where students use circular reasoning that restates claim rather than explaining connection - saying 'The bottle fell, so the bottle fell' doesn't actually explain how the observation supports the claim about gravity. To help students: Practice adding missing components to incomplete arguments using sentence starters: 'This evidence supports the claim because...' or 'This shows that gravity... because...' Watch for: Students who confuse reasoning (how evidence connects to claim) with more evidence or who provide circular explanations that don't add new understanding.