20
Operations with numbers 1 to 5
Textbook Part 1, pp. 42–43
GoalAdd and subtract using a ruler (number line).
New words
operation · amalruler · chizg‘ichnumber line · sonlar nurijump right / left · o‘ngga / chapga sakramoq
Explanation
The numbers on a ruler are in order. To add we jump right; to subtract we jump left. 3 + 2: start at 3 and jump 2 steps right — we land on 5. 5 − 2: start at 5 and jump 2 steps left — we land on 3.
Worked examples
0 1 2 [3] → 4 → 5 : 3 + 2 = 5
4 − 1 − 1: from 4 jump left by 1 twice — 2.
Class activity
Draw a number path from 0 to 5 on the floor. A child says a sum and hops along the numbers to find the answer.
Practice
1
With a ruler: 2 + 3 = ?
5
2
With a ruler: 5 − 3 = ?
2
3
4 − 1 − 1 = ?
2
4
Put the sign: 2 + 2 ... 5
<