Right Angles, Squares and Rectangles
Primary 1 · Mathematics
Right Angles, Squares and Rectangles
Lesson 3 of 5
12 min
Let's begin
Keza waits outside a shop in Kigali. The floor there has flat tiles.
She walks along one tile, heel to toe. Then she walks along the next side.
Both walks take the same number of steps. Today you will learn why.
Look at one floor tile.
Rule 1. It has 4 straight sides, and all 4 sides are the same length.
Rule 2. It has 4 right angles.
A shape needs both rules. Then it is a square.
| What to check | A square has |
|---|---|
| Straight sides | 4 |
| Sides the same length | all 4 |
| Right angles | 4 |
Cut a piece of string as long as one side of the tile.
Hold it along the next side. The same length!
Do the other two sides too. All 4 are the same.
Push your book corner into each corner of the tile.
No gap. No gap. No gap. No gap.
That is 4 right angles. Both rules are true, so the tile is a square.
Ishimwe cuts a square from paper. It sits flat on the desk.
Now he turns it to stand on one point.
Has anything changed? Count the sides. Still 4, all the same length.
Test the corners. Still 4 right angles.
Both rules are still true. It is still a square.
Careful! Some children call a turned square a diamond. The shape did not change, only the way it sits. Check the rules, not the picture.
Mutesi draws three shapes on her page.
Shape 1 has 4 equal sides and 4 right angles. It sits flat.
Shape 2 is the same shape, turned to stand on its point.
Shape 3 has two long sides and two short sides.
How many squares? 2. Shapes 1 and 2 both pass the rules.
Children who count only 1 forgot the turned one.
4 sides, all the same length. Turned squares too.
Sing the square song with Akili and her friends.
Tip
Turn it around. Still a square
Say the two rules out loud: 4 sides the same, 4 right angles.
A shape is named by its rules. It is never named by the way it is lying.
Check both rules each time. Then tap Show answer to check.
How many sides does a square have?
Answer: 4. And all 4 are the same length.
How many right angles does a square have?
Answer: 4. Test every corner with your book.
Keza turns a square to stand on its point. Is it still a square?
Answer: yes. Turning never changes the rules.
A shape has 4 right angles. Two sides are long and two are short. Is it a square?
Answer: no. The sides are not all the same length.
Fold a square from paper. Cut it out. Check all 4 sides against each other.
Answer: every side lies exactly on the next one.
What you learned today
Quick check
A square has how many right angles?
