My brilliant idea - Leap frogs

2nd January 2009, 12:00am

Share

My brilliant idea - Leap frogs

https://www.tes.com/magazine/archive/my-brilliant-idea-leap-frogs

Maths

Ages 7-14

Down at the maths pond, four frogs each sit on a pentagonal lily pad. Two red frogs with triangular eyes are sitting on one side and two yellow frogs with lozenge-shaped eyes sit on the other. There is one lily pad between them.

One day the frogs decide to swap sides. However, the law of the land says that frogs must abide by four rules: (1) frogs can only move one at a time, (2) there can only be one frog on a lily pad at any time, (3) frogs can slide on to the adjacent lily pad and (4) frogs can only jump over one frog forwards or backwards.

What is the least number of moves it takes for the frogs to change sides?

The frog puzzle is a delightful challenge to inspire problem solving and planning ahead. Children take the place of the frogs and chairs become lily pads. The rest of the class can call out and tell which frog to move. You can then build up to three, four, five, six or seven frogs on each side.

The problem can be extended by having an unequal number of frogs on each side or having two spare lily pads in between

John Dabell teaches at Lawn Primary School in Derby.

Want to keep reading for free?

Register with Tes and you can read two free articles every month plus you'll have access to our range of award-winning newsletters.

Keep reading for just £1 per month

You've reached your limit of free articles this month. Subscribe for £1 per month for three months and get:

  • Unlimited access to all Tes magazine content
  • Exclusive subscriber-only stories
  • Award-winning email newsletters
Recent
Most read
Most shared