Two designs can solve the same problem in different ways. Use the same test for each. A stronger design might need more folds. We will compare a flat bridge and a folded bridge, not decide which looks nicest. Safety: Work on the floor away from feet; use stable books and only the light pencil load. Stop: End after six trials and one improvement sketch. Do not add heavier loads or increase the gap.

Materials: Two sheets of the same paper; Two equal-height stable books; One wooden pencil, ruler, paper and pencil for records 1. Place the books 10 cm apart on the floor. State the problem: carry one wooden pencil across this gap without the bridge touching the floor. 2. Leave sheet A flat. For B, fold alternating strips about two finger-widths wide across the sheet to make an accordion. Position each bridge across the gap with the same overlap at each end. Position the folds along the span between books. 3. Make a table Design | Trial 1 | Trial 2 | Trial 3. Put the same wooden pencil at the centre for a slow count to five. Record holds or touches floor. Remove the pencil and reset the bridge for each trial. 4. Compare the number of successful trials. Also record which design was easier to prepare. Name one strength and one weakness of each, including collapse if it occurred. 5. Recommend a design for this one-pencil problem using a result from the table. Sketch one improvement and say what a later test would need to check. Done: Both designs have three actual trial records and a recommendation tied to those records. Proof: Keep the results table and improvement sketch. Note adult folds, resets or counting. Stop: End after six trials and one improvement sketch. Do not add heavier loads or increase the gap.