105
Mass: word problems
Textbook Part 3, pp. 64–65
GoalSolve one- and two-step problems about mass; count in threes.
New words
sack · qopwheat · bug‘doyflour · unmill · tegirmon
Explanation
Mass problems are solved just like part-whole and more-fewer problems. “One sack has 30 kg and the other 2 kg more” → the second has 32 kg, in all 30 + 32 = 62 kg.
Worked examples
8 kg of flour was taken from a sack and 6 kg is left. At first: 8 + 6 = 14 kg.
A mill grinds 3 kg at a time: 2 times — 6 kg, 3 times — 9 kg, 5 times — 15 kg (counting in threes).
Class activity
Counting in threes: in a circle, children take turns saying 3, 6, 9, 12, 15… and each adds one “sack” (a block).
Practice
1
One sack has 30 kg of wheat and the other 2 kg more. In all?
62 kg
2
8 kg of flour was taken from a sack and 6 kg is left. How much was there?
14 kg
3
Count in threes: 3, 6, 9, _, _
12, 15
4
One truck carries 40 sacks. How many trucks for 90 sacks?
3 (40 + 40 + 10)