TimeTime

Learning IntentionLearning Intention Success CriteriaSuccess Criteria

2.2. Change from 24 to 12 Change from 24 to 12 hour clock.hour clock.

1. To revise previous work on converting between 12 and 24 hr clock and vice versa.

Revision

1.1. Change from 12 to 24 Change from 12 to 24 hour clock.hour clock.

Converting TimeConverting Time

2300220021002000190

018001700160015001400

1300

1200

11 pm

10 pm

9 pm8 pm7

pm6 pm5 pm4 pm3 pm2 pm

1 pm

midday

1100100009000800070

006000500040003000200

0100

0000

11 am

10 am

9 am8 am7 am6 am5am4 am3 am2 am1

ammidnigh

t

12/24 Hour Clock

To go from 12 hour clock to 24 hour clock just add 12 to the pm hours:

2000 2100

1830 2330

1620

Examples

8 pm becomes

9 pm becomes

6:30 pm becomes

11:30 pm becomes

4:20 pm becomes

3:10 pm becomes

1510

2300220021002000190

018001700160015001400

1300

1200

11 pm

10 pm

9 pm8 pm7

pm6 pm5 pm4 pm3 pm2 pm

1 pm

midday

1100100009000800070

006000500040003000200

0100

0000

11 am

10 am

9 am8 am7 am6 am5am4 am3 am2 am1

ammidnigh

t

12/24 Hour Clock

To go from 24 hour clock to 12 hour clock just subtract 12 from the hours if it is greater than 12:

8 pm 9 pm

5:30 pm 10:08 pm

8:06 pm

Examples

2000 becomes

2100 becomes

1730 becomes 2208 becomes

2006 becomes 1350 becomes 1:50 pm

greater than 12 subtract 12

Let’s make up our own questions !

Converting TimeConverting Time

Key Points

12 hour clock

Analogue clock

ALWAYS use AM or PM

24 hour clock

Digital clock

NEVER use AM or PM

pm times add on 12

ALWAYS 4 digits

Hours 0 - 24

Hours 1 - 12

Counting Counting MethodMethod

When working out time difference we will use the Counting Method. This method will always work.

Example : Find the time difference between 08 40 hrs and 11 10 hrs

08 40 11 00 11 10

Hrs Mins

20

210

2 30

nearest hour What’s left

+09 00

hours

20 mins 2 hrs 10 mins

A bus leaves Kirkintilloch Main Street at 14 40 hrsand arrives in Aberdeen at 18 50 hrs. How long was the journey.

Counting Counting MethodMethod

14 40 18 00 18 50

Hrs Mins

20

350

3 70

nearest hour What’s left

+

15 00

hours

20 mins 3 hrs 50 mins

But there are 60 minutes = 1hour

70 mins = 1hr 10mins

4hrs 10 mins

Using Timetables

2314

2302

2254

2248

2243

2237

2225

2214

2202

2154

2148

2143

2137

2125

2114

2102

2054

2048

2043

2037

2025

Until

Hour

Every

And

1114

1102

1054

1048

1043

1037

1025

1014

1002

0954

0948

0943

0937

0925

0914

0902

0854

0848

0843

0837

0825

Glasgow Bus Station

George Square

Port Dundas

Springburn

Milton

Bishopbriggs

Kirkie Bus Station**

*How long does the first bus take from Kirkie to Glasgow.

35

014

Hrs Mins

49+

08 25 09 00 09 14

nearest hour What’s left

09 00

hours

35 mins 0 hrs 14 mins

350

14

Let’s make up our own question !The key steps are left on the slide to help you.

Counting Counting MethodMethod

Hrs Minsnearest

hour What’s left

+

hours

mins hrs mins

But there are 60 minutes = 1hour

Counting Counting MethodMethod

Learning IntentionLearning Intention Success CriteriaSuccess Criteria

1. To work out accuracy to 1 and 2 decimal places.

1.1. Round to 1 and 2 decimal Round to 1 and 2 decimal places.places.

TimeTimeMinutes and Secs

TimeTimeMinute & Seconds

Rounding time to 1 or 2 decimal places is just the same as rounding any number.

Example : Round the times to 1 and 2 decimals places

(a) 4.573 secs 4.6 secs to 1 decimal place

4.57 secs to 2 decimal place

(b) 52.455 secs 52.5 secs to 1 decimal place

52.46 secs to 2 decimal place

TimeTimeMinute & Seconds

Note : In athletics the winner of a race corresponds tothe smallest time.

Example : In a race the times are as follows Mark 11.01 sec, Caitlin 10.05sec, Owen 10.03 sec, Amy 10.92 sec and Euan 10.73 sec.

Work out who won the race and the order they came in. 1st Owen 10.03 sec

2nd Caitlin 10.05sec

3rd Euan 10.73 sec

4th Amy 10.92 sec

5th Mark 11.01 sec

TimeTimeMinute & Seconds

Example : In a race Katrina beat Daniel by 0.53 sec. Daniel’s time was 10.46 secs.

What was Katrina’s time ?

Katrina won therefore her time will be 0.53 less.

0 9 1 1 0. 46

- 0. 53

9. 93