Perimeter: walk the edge

What this lesson shows

Lay unit segments along a 5 by 3 rectangle with no gaps. The perimeter is 16 units.

The worked example

The lesson works this one step by step: 5 by 3. Then your kid tries one like it on paper.

The steps

1. Perimeter: around the edge
2. Count each unit
3. Back to the start
4. Write the units

Helping at home

Trace the edge with a finger. Start at a corner and count each unit length around until you are back where you started. That count is the perimeter, in units.

If your kid gets stuck

Start at a corner.

More in this unit

• Naming flat shapes
• Turned, still a square
• Count sides, not looks
• Sorting shapes
• A square is a rectangle too
• Not every half is a mirror
• More sides, not more lines
• Count each unit once
• Perimeter by adding sides
• Opposite sides match
• Perimeter of a pentagon
• Rows and columns of squares
• Faces, edges, and corners