Time, Liquid Volume, and Mass: practice solutions, Grade 3 – download the PDF

1 Read the clock ★★★

(a) The hour hand has just passed 3, and the minute hand is two marks past the 8. The 8 stands for 40 minutes, so the time is 3:42.

(b) \(60 - 42 = 18\). It is 18 minutes until 4:00.

2 Counting by fives ★★★

Count by fives: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55.

(a) The 7: 35 minutes. (b) The 9: 45 minutes. (c) The 4: 20 minutes. (d) The 11: 55 minutes.

3 Another clock ★★★

The hour hand is just past the 6, so the hour is 6. The minute hand is three marks past the 3. The 3 stands for 15 minutes, and three marks make 18 minutes. The time is 6:18, which is 18 minutes after 6:00.

4 A short movie ★★★

From 4:10 to 4:50, count the minutes: \(50 - 10 = 40\).

The cartoon lasts 40 minutes.

5 Convert the units ★★★

Remember \(1\text{ L} = 1{,}000\text{ mL}\) and \(1\text{ kg} = 1{,}000\text{ g}\).

(a) \(3 \times 1{,}000 = 3{,}000\) mL. (b) \(5{,}000 \div 1{,}000 = 5\) L. (c) \(2 \times 1{,}000 = 2{,}000\) g. (d) \(4{,}000 \div 1{,}000 = 4\) kg.

6 Choose the best unit ★★★

(a) A spoonful is very small: mL. (b) A bathtub holds a lot of water: L. (c) A paper clip is very light: g. (d) A watermelon is heavy: kg.

7 Read the beaker ★★★

(a) The level is halfway between the 300 mark and the 400 mark, so the beaker holds 350 mL.

(b) \(500 - 350 = 150\). You need 150 mL more.

8 Soccer practice ★★★

Jump along a number line.

From 3:25 to 4:00 is 35 minutes. From 4:00 to 4:10 is 10 minutes. \(35 + 10 = 45\).

Practice lasts 45 minutes.

9 When did the bus leave? ★★★

Go backward from 8:20. First jump back 20 minutes to 8:00. Then jump back \(35 - 20 = 15\) more minutes to 7:45.

Check: 7:45 plus 35 minutes is 8:20.

The bus left at 7:45 a.m.

10 Cookies in the oven ★★★

From 5:40, jump 20 minutes to 6:00. There are \(25 - 20 = 5\) minutes left to add, so the time is 6:05.

She should take them out at 6:05 p.m.

11 The lemonade pitcher ★★★

Lemonade poured: \(4 \times 250 = 1{,}000\) mL.

The pitcher held \(2 \times 1{,}000 = 2{,}000\) mL, and \(2{,}000 - 1{,}000 = 1{,}000\) mL remain.

There are 1,000 mL left, which is 1 L.

12 The backpack ★★★

Add: \(450 + 275 = 725\), then \(725 + 600 = 1{,}325\).

The total mass is 1,325 g, which is 1 kg 325 g.

13 True or false? ★★★

(a) True. \(2{,}000 + 500 = 2{,}500\) g.

(b) False. \(3{,}000 \div 1{,}000 = 3\), so 3,000 mL is 3 L.

(c) True. 4 kg is 4,000 g, and 4,000 is greater than 3,900.

(d) False. 5 kg is exactly 5,000 g, so they have the same mass.

14 The school schedule ★★★

(a) Art: 9:10 to 9:55 is \(55 - 10 = 45\) minutes. Reading: 10:05 to 10:50 is \(50 - 5 = 45\) minutes. Math: 11:00 to 11:50 is 50 minutes.

(b) Math is the longest, with 50 minutes.

(c) From 9:55 to 10:05 is 5 + 5 = 10 minutes.

15 Homework time ★★★

Math: 4:20 plus 25 minutes is 4:45, because \(20 + 25 = 45\).

Break: 4:45 plus 10 minutes is 4:55.

Reading: 4:55 plus 30 minutes is 5:25.

She finishes at 5:25 p.m. The total is \(25 + 10 + 30 = 65\) minutes.

16 A big pot of soup ★★★

Soup served: \(12 \times 250 = 3{,}000\) mL, which is 3 L.

Soup left: \(6 - 3 = 3\) L.

There are 3 L of soup left.

17 The fruit crate ★★★

Melons: \(4 \times 3 = 12\) kg. Add the grapes: \(12 + 5 = 17\) kg.

Room left: \(20 - 17 = 3\) kg, and \(3 \times 1{,}000 = 3{,}000\) g.

The crate can hold 3 kg (3,000 g) more.

18 Make a reasonable estimate ★★★

(a) 2 kg: it is heavier than a few paper clips but easy to carry in a bag.

(b) 10 L: 1 mL is a few drops, and 1,000 L is a huge tank.

(c) 4 kg: 400 g is about the mass of two apples, and 40 kg is a large dog.

19 Two jugs and a bowl ★★★

Change 1 L 50 mL to \(1{,}000 + 50 = 1{,}050\) mL.

Total: \(1{,}200 + 1{,}050 = 2{,}250\) mL, or 2 L 250 mL.

The bowl holds 3,000 mL, so the room left is \(3{,}000 - 2{,}250 = 750\) mL.

The bowl holds 2,250 mL and has 750 mL of room left.

20 The long hike ★★★

(a) From 11:50 a.m. to 12:00 p.m. is 10 minutes. From 12:00 to 1:00 p.m. is 60 minutes. From 1:00 to 1:15 is 15 minutes. \(10 + 60 + 15 = 85\).

The hike lasts 85 minutes, which is 1 hour 25 minutes.

(b) \(3 \times 750 = 2{,}250\) mL. They carry 2,250 mL, which is 2 L 250 mL.