Symmetry and Solid Shapes
Visualising solid shapes
Count the faces, edges and vertices of a solid, tell flat surfaces from curved ones, and say what a solid looks like from another direction.
A solid takes up space, so it has three things worth counting. A face is a flat surface you could rest it on. An edge is the line where two faces meet. A vertex is a point where edges meet — what you would ordinarily call a corner.
Have a play
A cube, drawn on flat paper. Find out what each part of it is called.
Tap any part of the picture.
Nets
A net is a solid unfolded flat. A cube's net is six squares joined so they fold back into a box — and not every arrangement of six squares works, which is what makes nets worth thinking about rather than just drawing.
Worked example
How many faces, edges and vertices does a triangular prism have?
Faces: the two triangles at the ends, plus three rectangles round the sides. That is 5.
Counting by kind — the ends first, then the sides — stops you counting one twice.
Try it together
Now let us count the parts of a square pyramid together.
A square pyramid has a square base and four triangles leaning in to meet at a point on top.
1.How many faces does it have altogether?
Have a go
Have a go on your own: how many edges does a triangular prism have?
Hint: Three round each triangle, and some joining the two ends.
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.