Lesson 4: Building Strong Structures
Structures need to support loads — the weight of people, objects, wind, and even earthquakes. Engineers use shapes and materials cleverly to make structures strong and stable.
Key Concepts
Triangles Are the Strongest Shape
A triangle cannot be deformed without changing the length of its sides. Squares and rectangles can be pushed into parallelograms, but triangles hold their shape. That is why bridges, towers, and roofs use triangles everywhere.
Load and Stress
A load is a force on a structure. Compression pushes materials together (pillars are in compression). Tension pulls materials apart (suspension bridge cables are in tension). Good structural design manages both.
Foundation Matters
A structure is only as strong as its foundation. Wide bases are more stable than narrow ones. Deep foundations in solid ground support skyscrapers. Engineers test soil before building.
🆕 Tower Builder
Add floors to your tower. Use triangles to brace it — see how stable it is!
✅ Check Your Understanding
1. Why do engineers use triangles in structures?
2. What is compression?
3. Why does a wide base make a structure more stable?