Today you are going to be

estimating the answers to questions.

5.823 - 2.24 178 × 0.023

9.876 × 10-1 + 2.61 (8.23 × 102) ÷ (1.774 × 102)

20

The Dashed Zone

The Dashed Zone

The Solid Zone

The Solid Zone

………………………………………………………………………………………… by …………………………………………………………

0.546 × 0.633

92.7 – 28.76

98 × 4.234

0.323 + 0.47

224 + 316

11432 ÷ (2.3× 102)

4.4 ×102 ÷ (5.23 ×102)

(937 – 469) × 10-2

(1.2 × 105)

÷ (1.5 ×102)

3.68 × 4.01 ÷ (2.33 × 10-1)

83 ÷

(2.3 × 10-1)

9.822 - 4.5 × 3.7

-(244-487)

3.8 × 10-1 + 1.8 × 10-1

7.622 – 2.32

0.0034 × 175

0.145 ÷ 0.0018

93.7 ÷ 271

Questions Your teacher

4.18 + 1.49

2.45 × 102

÷ 39

2.071 × 1.663

(634 ÷ 192)2

)96886(

8650 ÷ 978

You are going to use what you’ve just learned to play a game.

The aim of the game is to form a pathway from one side of the board to the other by

finding matching pairs of answers.

Player 1 finds a matching pair and places TWO of their counters on those formulae.

Then Player 2 does the same.

The winner is the first person to complete a pathway (from either the Dashed Zone to the Dashed Zone or the Solid Zone to

the Solid Zone).

The Dashed Zone

The Dashed Zone

The Solid Zone

The Solid Zone

Your pathway could look like this:

The Dashed Zone

The Dashed Zone

The Solid Zone

The Solid Zone

Or this:

The Dashed Zone

The Dashed Zone

The Solid Zone

The Solid Zone

Or this:

If you do not feel confident about estimating answers or playing the game then you can just match up the answers

and colour in the pairs.

You may work by yourself or with a friend.

The Dashed Zone

The Dashed Zone

The Solid Zone

The Solid Zone

………………………………………………………………………………………… by …………………………………………………………

0.3

60

300 400

0.8500

50

0.8

9

4

500

80

400

80

300

5

0.6

60

4

0.6

50

0.3

9

5

Answers Your teacher

Today you have been estimating answers.

Which is smaller

0.85 ÷ 2.66 or 5720 ÷ 32644?

Which is smaller

5.76 x 102 + 18.87 or 24 x 32?

Which is smaller

0.17 x 0.22 or 8.35 x 10-1 ÷ 1.83?

Lesson Plan

Starter (10 mins)Show slide 2. Ask students ‘What do you think goes in the middle box?’ or ‘What do these questions have in common?’. You could then ask students to discuss their ideas with the person next to them. They should quickly realise that a estimate of each of the answers is 4.Show slide 2. Ask students to create a similar question which would produce the answer 20. Ask for volunteers to come forward and share their questions with the rest of the group. Discuss whether the students’ questions are right or wrong.

Main Activity (30 mins)Show slides 4 to 9. Students are to either play the game or simply colour in matching answers. They may work in pairs or alone. This activity can be extended by asking students to create their own board. The answers are on slide 10 if required.

Plenary (10 mins)Show slide 11. Students independently decide which formula gives the smaller answer. They indicate their decision by raising their right or left hand on command. Warning – the third question will need discussing – estimating to 1sf gives the wrong answer.

Resources: Printed game sheets, counters.