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Hmm ... When Should Tom Have Put the Rice on ...

Age 11 to 16
Challenge Level Yellow star
  • Problem
  • Student Solutions
  • Teachers' Resources

Why do this problem?

This is one of a series of problems which students might encounter in Food Technology. 
The problem originated in a real situation when someone cooked a beautiful meal, only noticing in the last five minutes that the recipe said 'Serve with rice' - by which time it was too late, if the rest wasn't to be ruined.
Mathematically, it gives practice in organising information.  One way to tackle it would be to draw a flow chart, then put times onto each stage.  Alternatively, students could use a Gantt chart.

Key questions

Do you have all the information you need to get started?  If not, how can you find it?

Are you going to start from the beginning of the recipe or the end, working backwards?

Do you need to start with just one flow chart, or two?

Possible extension

Olympic Logic gives students a good work-out in logical thinking.

Possible support

Tom Learns to Cook is a simpler problem requiring scheduling stages in cooking a meal.

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Toad in the Hole

Is it cheaper to cook a meal from scratch or to buy a ready meal? What difference does the number of people you're cooking for make?

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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