Time calculations

Time calculations

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
 
This task is about working out the difference between two times.
 

Question 1Change answer

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a)  At 16:00 in 24-hour clock time, the school bus dropped Luka at his gate.
     How many minutes after 15:00 is this?

Question 1Change answer

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b)  A car ride lasted from 14:40 to 15:46.
     How many minutes is this?

Question 1Change answer

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c)  Bruce and Allan agree to meet at 17:35. 
     If the time is 16:15, how long is it before they meet?

Question 1Change answer

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d)  Mrs Jones cooked for 4 hours 30 minutes. 
     If she started at 9:45, what time did she finish? 

     Write your answer in 24-hour clock time.  : 
Task administration: 
This task can be completed with pen and paper or online (with NO auto marking).
Level:
4
Curriculum info: 
Maths, Geometry and Measurement, Measurement
Keywords: 
time, 24-hour time, addition, subtraction
Description of task: 
Students work out time calculations involving 24 hour time.
Curriculum Links: 
This resource can help to identify students' understanding of working with 24 hour time for the Measurement objectives and additive strategies for the Number and Algebra objectives.
 
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Additive thinking, sets 7-8
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y8 (05/1998)
a) 60  [accept 1 hour] very easy
b) 66 minutes or 1 hour 6 minutes easy
c) 80 minutes or 1 hour 20 minutes moderate
d) 14:15 moderate
Diagnostic and formative information: 
  Common error Likely calculation Likely reason
b) 29:86
106 min		 14:40 + 15:46 Adds times and assumes 1 hour = 100 min.
Writes 1 hr 6 min as 106 min.
c) 120 min   Subtracts as if 100 min = 1 hour.
d) 13:75 13:00 + 0:75 Fails to recognise 60 min = 1 hour.
d) 13:15   Fails to 'carry' extra hour.