Bridge Builder

Bridge Builder is a free bridge-building game. Students build a bridge from road, wood, steel and cables, then drive a car, a truck or a crane across it. The game works out the force in every beam the way structural engineers do (the direct stiffness method). Beams snap when they’re pulled too hard, crush or buckle when they’re squashed, and bridges without triangles fold up.

How to play

Choose Road and drag along the dashed line from one bank to the other. Then add wood and steel beams to hold it up, joining the points of the grid. Tick Show forces to colour every beam: blue is pulled (tension), orange is squashed (compression), and red is over its limit. When you’re ready, press Drive and watch your bridge take the load.

Each level earns up to three stars: one for getting across, two for staying within the budget, and three for matching the cheapest design we know.

The levels

#	Level	Years	Big idea
1	Mind the Gap	8	Triangles make structures rigid
2	Triangle Power	8	Trusses
3	Push and Pull	9	Tension and compression; strong material where forces are big
4	Low Bridge	9–10	Building under the road; arches
5	Buckle Up	10–11	Buckling gets worse with length; Pratt trusses
6	Go Deeper	11–12	Chord force = bending moment ÷ depth
7	Cable-Stayed	11–13	Cables only pull; cable-stayed bridges
8	Heavy Haul	12–13	Supports in the middle; everything combined

Tips for teachers

• Years 8–9: let students build a bridge without triangles first and watch it fold. Then ask them why triangles fix it.
• Years 9–11: with Show forces on, ask which beams are pulled and which are squashed, and where the steel should go. Buckle Up shows why long beams in compression are risky.
• Years 11–13: Go Deeper links truss depth to the bending moment, and Cable-Stayed and Heavy Haul are open design challenges. The 3-star target rewards efficient structures.

Every level ends with a short “What you learned” summary you can use as a plenary.