Marcus and Yuki must coordinate during a game without opponents knowing. Solution A uses shoe-lace signals: left lace tucked=“pass,” right lace tucked=“shoot,” both tucked=“slow down.” Solution B uses hand signals: touch ear=“pass,” touch nose=“shoot,” hands on hips=“slow down.” Which solution would be better if opponents are watching closely for clues?
- Solution B because big hand signals are easier for teammates to see quickly.
- Solution A because small lace changes are less noticeable than obvious hand movements. (correct answer)
- Solution B because touching your face is more secret than changing your shoes.
- Solution A because lace signals can be heard, but hand signals cannot be heard.
Explanation: This question tests 4th grade ability to compare multiple pattern-based information transfer solutions using clear criteria (NGSS 4-PS4-3). Students must evaluate alternatives based on specific requirements and recognize tradeoffs. To compare solutions: (1) Identify the criteria (what's important? - clarity, distance, speed, secrecy, ease), (2) Examine each solution's features (how does it work? what are characteristics?), (3) Match features to criteria (which solution best meets this requirement?), (4) Consider tradeoffs (what does each gain/lose?), (5) Choose based on priorities (what matters most for this situation?). Good solutions have advantages for some criteria but may have limitations for others - no perfect solution usually. The 'best' solution depends on what criteria matter most for the specific problem. In this problem, the criterion is avoiding detection by opponents watching closely. Solution A uses shoe-lace signals (tucking laces - subtle, low body position). Solution B uses hand signals (touching face parts - more obvious, upper body movements). For avoiding detection, Solution A is better because small lace adjustments at shoe level are less noticeable than obvious hand movements to the face that opponents watching for clues would easily spot. Choice B is correct because it accurately identifies that Solution A is better for avoiding detection and provides valid reasoning: small lace changes are less noticeable than obvious hand movements. This demonstrates understanding that solutions can be compared systematically using criteria and that the best choice depends on what the situation requires, not just which solution is 'better' overall. Choice A is incorrect because it claims big hand signals are easier for teammates to see quickly, which addresses visibility to teammates but ignores the stated criterion of avoiding opponent detection. This error occurs when students focus on a different criterion than what's asked or don't understand that being easy to see is bad when trying to be secret. The key understanding: Different solutions excel at different things - must match solution strengths to problem requirements. To help students compare solutions: Teach systematic comparison process - create comparison table with solutions as columns and criteria as rows, fill in how each solution performs on each criterion. For each comparison: (1) Clarify criterion (what are we judging?), (2) Examine each solution for that criterion (which has advantage here?), (3) Identify tradeoffs (what does it gain/lose?). Practice with clear examples: Solution A (light flashes) - good for distance, doesn't work in bright sun; Solution B (hand signals) - good for secrecy, only works if can see each other; Solution C (sounds) - works in dark, doesn't work if noisy. Ask: Which for secret team play? Emphasize: No solution perfect for everything. Best choice = solution whose strengths match problem's priorities. Real engineering means evaluating tradeoffs and choosing appropriately for situation.