2
Halves, thirds and fourths
Discover Mathematics P2: Term 2, Lessons 101–110
GoalName equal parts as halves, thirds and fourths.
New words
half · one of 2 equal partsthird · one of 3 equal partsfourth · one of 4 equal parts, also called a quarterwhole · all the parts together
Explanation
When a whole is cut into 2 equal parts, each part is a half. When it is cut into 3 equal parts, each part is a third. When it is cut into 4 equal parts, each part is a fourth, or a quarter. 2 halves make one whole. 3 thirds make one whole. 4 fourths make one whole. The more equal parts there are, the smaller each part is.
Worked examples
A round flatbread is cut into 2 equal parts. One part is one half of the flatbread.
A ribbon is folded into 3 equal parts. One part is one third of the ribbon.
A pizza is cut into 4 equal slices. One slice is one fourth, or one quarter, of the pizza.
Class activity
Fold a paper strip. Fold it in half and open it: 2 equal parts. Take a new strip and fold it into 4 equal parts by folding in half twice. Colour one part. Colour a different strip so that 1 of 3 equal parts is coloured. Write the name of each part.
Practice
1
A pizza is cut into 4 equal pieces. What is each piece called?
A fourth, or a quarter.
2
How many thirds make a whole?
3 thirds.
3
How many equal parts does the whole have, and how many are coloured?
3 equal parts, and 2 are coloured.
4
Which part is bigger: one half or one fourth of the same flatbread?
One half. When there are fewer parts, each part is bigger.
5
Marina folds a paper strip in half. Then she folds it in half again. How many equal parts are there now?
4 equal parts. Each part is a fourth.