Primary 2 · Mathematics
P2 shapes and patterns
Ask how many flat faces a cylinder has and the answer is often 3. The counting is fine. The round side just is not a flat face, and a tin rolled across the table makes the difference obvious.
- Level
- P2
- Usually taught
- Term 4
- Covers
- 3 concepts
What changes at P2
In Primary 2 your child names the 3D shapes: cube, cuboid, cone, cylinder and sphere. Each is described by its surfaces. A flat face lets a solid stack or slide, and a curved surface lets it roll.
The topic also covers repeating patterns of shapes, which can change by size, shape, colour or the way a shape is turned. The first job is to find the part that repeats and name what changes.
The sentence that costs the mark
How many flat faces does a cylinder have?
What the working usually does
flat faces on a cylinder:every surface=3
Counts the top, the bottom and the round side.
What the question asked
flat faces on a cylinder:flat ones only=2
Sorts the surfaces first. The round side is curved.
All three surfaces were found and counted correctly. The question turns on one word, flat, and it is an easy word to read past when the counting feels like the hard part.
The same question, worked properly
Point at every surface
top, bottom, round sideTouch each one as you name it, so none is missed or counted twice.
Sort them into flat and curved
the round side is a curved surfaceThis is the step that fails. A curved surface is not a flat face, so it drops out of the count. Counting every surface at once misses this.
Count the flat ones
2 flat facesA cylinder has 2 flat faces and 1 curved surface. Sorted the same way, a sphere has no flat faces at all.
How can you tell it has clicked?
Ask how many flat faces a cone has. A child who sorts first says 1, and may add that the point is not a face. An answer of 2 means the curved surface was counted too.
For patterns, ask what comes next, then ask why. "Because it goes square, circle, circle" shows the repeating part was found. "Because the last one was a circle" is a guess from the item before, and it breaks as soon as the pattern turns.
One thing to try tonight
Take a tin from the kitchen cupboard, roll it across the table, then stand it up. Ask which surfaces it rolls on and which it stands on.
The ones it stands on are the flat faces, and there are two. Try a ball next: it rolls every way and stands on nothing, which is why a sphere has no flat faces.
What your child will meet in this topic
- 3D Shapes
- Repeating Patterns
- 2D Shapes
Most Singapore schools introduce this in Term 4, though schools do differ by a term either way. If your child’s school runs a different order, you can set it in the schedule on your dashboard.
What it leads to
P3 turns to angles and to perpendicular and parallel lines, where shapes are described by their corners and edges rather than their surfaces.
In P4 the flat faces come back in nets: a cube's six flat faces laid out as one flat shape that folds up into the solid.
The same topic in other years
It comes back each year and gets harder, so it helps to see what came before and what is coming.
More in Primary 2
Other topics in the same year, so you can see what sits either side of this one.
See how your child is doing on this topic
StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.