Primary 1 · Mathematics

P1 shapes

A square turned on its corner is still a square, but it is often given another name and left out. The fix takes one square cut from a cereal box.

Level
P1
Usually taught
Term 1
Covers
1 concept

What changes at P1

In Primary 1 your child learns six flat shapes: rectangle, square, triangle, circle, half circle and quarter circle. They name each one by its sides and corners, and they find the shapes that a bigger figure is made up of.

They also copy figures onto a grid of dots. Both jobs rest on one idea. A shape is decided by its sides and corners, and turning it or sliding it across the page changes neither.

The sentence that costs the mark

A worksheet shows two shapes, one sitting flat and one turned on its corner. Circle the squares.

What the working usually does

judge by:how it sits=not a square

Sees a shape standing on a point and calls it something else, so only one is circled.

What the question asked

judge by:sides and corners=a square

Counts 4 equal straight sides and 4 square corners, so both are circled.

The child is confident, and "diamond" is a real word for the turned one, so nothing about the answer looks like a reasoning error. On the page it looks like one missed item. The mistake is naming the picture's position instead of the shape.

Sitting flat
Turned on its corner

The same question, worked properly

  1. Count the sides

    4 straight sides

    Point to each side in turn and count. Four sides, and none of them is curved.

  2. Check the sides

    all 4 the same length

    The small marks on the sides match, which is how a figure shows that sides are equal.

  3. Check the corners

    4 square corners

    Each corner is a square corner, like the corner of a page. The marker shows one of them.

  4. Turning it changes none of this

    4 equal sides, 4 square corners: a square

    This is the step that fails. The turned shape has the same sides and the same corners, so it is still a square. Naming it by how it sits is where the mark goes.

How can you tell it has clicked?

Draw a square, turn the paper so it stands on a corner, and ask what shape it is. If the name changes, your child is naming the picture. Then ask how many sides it has and whether they are the same length.

A child who answers "4 sides, all the same, 4 square corners, so it is still a square" has understood it. The same check works on a triangle drawn upside down, which is often left out for the same reason.

One thing to try tonight

Cut a square from a cereal box and ask what shape it is. Then turn it on its corner and ask again.

If the answer changes, count the sides together and turn it back. The card never changed shape, only the way it was sitting. Holding it in their own hands usually settles that faster than any drawing.

What your child will meet in this topic

  • 2D Shapes

Most Singapore schools introduce this in Term 1, 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

In P2, shapes become patterns, and there the turn is the point. A pattern can change by shape, size, colour or which way a shape faces. A child who knows that turning keeps the shape can see that the turn is what the pattern changes.

The square corner comes back in P3, where angles are compared against it before degrees arrive in P4. Naming shapes by sides and corners now is the start of that.

More in Primary 1

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.

Try it free