Cracked Clock

Topics: Starter | Arithmetic | Problem Solving

• Ruth Seward, Hagley Park Sports College
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• Find the starters wonderful; students enjoy them and often want to use the idea generated by the starter in other parts of the lesson. Keep up the good work
• Y8 set 1 Rawthorpe High School, The Cushtie Krew
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• We think that this was very good. We liked the clock, in fact we thought it was a cracking starter!
  Maths rules, Cushtie!
• Sue, St Albans
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• The question can be extended to 'the clock is broken into three pieces with equal sum of 26 -- piece one contains numbers 11, 12, 1, and 2; piece two contains 3, 4, 9, & 10; the rest is piece three'.
  Equally, it can be broken into 6 pieces with an equal sum of 13 -- piece one has 12 and 1; piece two has 2 and 11; piece three 3 and 10.
• Russ Skinner, Winnipeg, MB
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• This problem also works by breaking the clock into 3 pieces and 6 pieces. The sum of all the numbers around the clock (1 + 2 + 3...10 + 11 + 12) equals 78. 78 is divisible by 3 and 6.
• The Best Class Ever (8cd/m2), King Alfred's College OXON
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• We decided that this starter was not explained enough to work it out, so we tried both ways we could thing of and then realised that they were both the same answer.Tash, Ryan and Liam worked this out straight away with others not far behind them.
• Kieran, Weston
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• I found this easy to understand, and once I found pairs of 13 it was easy.

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