🎯 Learning intentions
- I can join my two trusses with cross members and deck sticks.
- I can explain why the deck distributes load across both trusses.
- I can keep the top surface flat for load testing.
✅ Success criteria
- Bridge has two trusses connected with at least 3 cross members.
- Deck surface is flat enough to lay a ruler across without gaps.
- Build journal photo 5 shows bridge from above (plan view).
Do Now · 5 min
Lay your two trusses on their sides with about 150 mm between them. Dry-fit a ruler across the top chords. Are they the same height? Record in folio: "Truss heights match: yes / no. Adjustment needed: ___."
I Do · ~10 min Teacher demonstration
Teacher models deck construction on the exemplar.
- Stand both trusses upright, parallel, 150 mm apart.
- Use masking tape to hold in position on the desk.
- Cut 3–5 cross members (short sticks) to join the top chords.
- Glue one cross member at each end first — that locks the position.
- Add more cross members evenly along the length.
- Then lay deck sticks along the top — these give you a flat surface to hang the bucket from.
We Do · ~15 min Guided practice
Together we draw a bird's-eye view of the deck on the board. Mark:
- Where the bucket will hang (centre of deck, between both trusses)
- Where load is highest (centre cross member)
- Where load is lowest (end cross members)
You Do · ~35 min Independent pair work
Build your deck (35 min).
- Position your 2 trusses upright, 150 mm apart, tape them to the desk.
- Cut 3–5 cross members.
- Glue ends first, then middle.
- Add deck sticks across the top.
- Check flatness — use a ruler. Any sticks sitting higher than others? Sand lightly or re-glue.
- Photo 5 from above for journal.
- Identify the strongest load point (where bucket will hang). Mark lightly in pencil.
Differentiation
🪜Support
Pre-cut cross members at exact lengths. Teacher sets truss-to-truss distance with jig.
🎯Core
Measure, cut, glue with partner.
🚀Extension
Add a load-spreading plate at the centre of the deck — a small piece of cardstock or laminated sticks.
Exit Ticket · 5 min
- What is the 'load path' in your bridge — trace it in one sentence.
- Where will you hang the bucket on test day?
- Is your deck flat? Check with a ruler and report.
📚 Resources for this lesson
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