110
Quantities and their properties (practice)
Textbook Part 3, pp. 74–75
GoalAdd quantities the easy way using grouping; find an unknown part.
New words
walnut / nut · yong‘oqraisins · mayizgrouping · guruhlash
Explanation
When adding several quantities, add the ones that make a round number first: 8 kg + 4 kg + 2 kg = (8 + 2) + 4 = 14 kg. The rule for an unknown addend works with quantities too: _ + 6 kg = 15 kg → 9 kg.
Worked examples
A bakery received 8 kg nuts, 4 kg raisins and 2 kg poppy seed: (8 + 2) + 4 = 14 kg.
_ l + 20 l = 50 l → 50 − 20 = 30 l
Class activity
Nut names game: children name kinds of nuts (walnut, almond, pistachio, hazelnut) and work out the expression card for each.
Practice
1
The easy way: 7 kg + 5 kg + 3 kg
15 kg
2
_ + 6 kg = 15 kg
9 kg
3
45 l − _ = 20 l
25 l
4
From the picture: 3 sacks — 10 kg, 20 kg, 5 kg. Total?
35 kg