122
Quadrilaterals
Textbook Part 4, pp. 24–25
GoalDefine a quadrilateral; recognise different quadrilaterals; write bracketed expressions.
New words
quadrilateral · to‘rtburchakrhombus · rombstage · sahnamusician · sozanda
Explanation
A shape made of 4 joined segments (sides) and 4 points (corners) is a quadrilateral. Squares, rectangles and rhombuses are all quadrilaterals, but their angles and sides differ.
Worked examples
A 6 cm by 3 cm rectangle: P = 6 + 3 + 6 + 3 = 18 cm.
Subtract the sum of 12 and 13 from 45: 45 − (12 + 13) = 45 − 25 = 20.
Class activity
Musicians puzzle: seat 8 musicians in a square room so there are 3 along each wall. Children try it with counters.
Practice
1
23 + (15 + 21) = ?
59
2
66 − (54 − 42) = ?
54
3
72 + (23 − 12) = ?
83
4
The musicians puzzle answer?
1 in each corner and 1 in the middle of each wall