✔ A cube has six square faces: top, bottom, front, back, left and right.
Q2. Siti counts edges of a triangular prism. How many?
✔ A triangular prism has three edges on the top triangle, three on the bottom and three vertical edges.
Q3. Wei Ming checks Euler's formula. F plus V minus E equals?
✔ For most convex solids, the number of faces plus vertices minus edges always equals two.
Show transcript
[Slide 1] Understanding Solids
Imagine a box at the hawker centre. The sides are faces, where they meet are edges. Corners are vertices like the MRT pillars.
[Slide 2] Counting Systematically
Always count in groups to avoid mistakes. A cube has six square faces and twelve straight edges.
[Slide 3] Ravi's Cube Frame
Ravi wants to make a cube frame for his project. We need to find the total length of wire first.
[Slide 4] Solving with Bar Model
We draw a bar for twelve edges of ten centimetres each. Siti helps calculate the cost at two dollars per metre.
[Slide 5] Common Mistakes to Avoid
Students often forget the edges at the back of the solid. Remember that vertices are just sharp corners, not lines.
[Slide 6] Key Takeaways
Remember the relationship between faces, edges and vertices. Practice counting on solids like prisms and pyramids.