Perimeter and area
Perimeter is the path around a shape; area is how many squares fit inside. Read one step, play with it, then tap “I understand this”.
Perimeter: the path around
Imagine an ant walking once all the way around the edge of a shape. How far it walks is the perimeter.
Walk around the rectangle
Change the length and width.
Perimeter = all the sides added together. For a rectangle: length + width + length + width.
Area: the squares inside
Area is how much space a shape covers. We measure it by counting how many squares fit inside.
Count the squares
Change the rectangle. See how rows × columns makes counting quicker.
Squares fit together with no gaps and no overlaps, so every bit is counted exactly once. Every row has the same number of squares, so 4 rows of 6 is 6 + 6 + 6 + 6 = 4 × 6.
Build your own shape
The building grid
Tap squares to build a shape. The blue line is the perimeter; the yellow squares are the area.
Same area, different perimeter
These three rectangles all have 12 squares, but their perimeters differ. A long, thin shape has a bigger perimeter.
Compare
Tap each rectangle.
Do not mix up perimeter and area. Perimeter is a length (cm, m); area is a number of squares.
Perimeter = around the edge (think of a fence). Area = the surface (think of a carpet).
In a long, thin shape almost every square touches the edge. In a squarish shape more squares are hidden inside, so there is less edge to walk around.
Volume: count the cubes
Volume is how much space something takes up. We measure it by counting how many cubes fill it. Count one layer and multiply by the number of layers.
Build a block
Change how long, wide and high the block is.
Count the cubes
Remember the cubes hidden at the back.
Correct: 0Check yourself
- Perimeter is the distance around (like a fence), in cm or m.
- Area is the number of squares inside (like a carpet).
- Rectangle: area = rows × columns.
- The same area can have a different perimeter.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Measurement8 pages · PDFPaperMemo
Ready for more? The Grade 4 perimeter and area quiz gives you new questions every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Measure the perimeter of a table together with a tape measure, and count the tiles on the kitchen floor: that is perimeter and area in your own home.
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 4 Maths. Always check your teacher’s notes and textbook too.