LOAD TEST DAY — the big weigh-in

Do Now · 5 min

Line up bridges at the front bench. Each pair hands in their build journal (PDF or printed). Weigh bridge one last time — record in class Google Sheet.

I Do · ~10 min Teacher demonstration

Teacher explains test procedure and safety.

1. Bridge placed across 350 mm gap on two stable benches.
2. Hanging bucket attached to deck centre.
3. Sand added in 250 g increments. Wait 10 seconds between additions.
4. Test stops at failure — any major structural break, deck buckling, or pair calls "stop".
5. Scale reading at failure = maximum load.
6. Everyone stays behind 1 m exclusion line during testing. Ms Gao only inside the zone.
7. Camera on. Every failure is recorded.

Ms Gao demonstrates with the exemplar bridge — this is the "benchmark to beat".

We Do · ~15 min Guided practice

First student pair's test. Whole class cheers as weights go on. Record their max load on the class leaderboard:

TEAM        MASS (g)    MAX LOAD (g)    RATIO
Bradfield   124         987             7.96
[YOUR NAME] ...         ...             ...

You Do · ~35 min Independent pair work

Your test (allow ~3 min per pair × 14 pairs = ~40 min). Rotate through:

1. Set up.
2. Prediction logged (final chance).
3. Load added in 250 g increments.
4. Failure — load recorded, photo taken, failure mode noted.
5. Calculate load-to-mass ratio: max_load (g) ÷ bridge_mass (g). Record.
6. Return to seat and fill in load test data table in your folio.

Part B submission: hand in physical bridge (even after failure — take broken pieces) + build journal. Ms Gao will photograph and log.

Differentiation

Exit Ticket · 5 min

1. Max load held: ___ g.
2. Bridge mass: ___ g.
3. Load-to-mass ratio: ___.
4. Failure mode: snap / buckle / joint separation / other?

📚 Resources for this lesson

• Class leaderboard
• Load-to-mass ratio calculator

Before you leave Quick check-in