a. Mark and Simon have birthdays on the same day. Mark is 7 years older than Simon.In 4 years from now he will be double Simon’s age.How old is Simon now?

b. Julie and Laura also have birthdays on the same day.Julie was 6 when Laura was born.Two years ago, Julie was three times Laura’s age.How old is Laura now?

AGE 9 - 13 Leapfrog

Draw a 5 x 5 grid of squares. Put nine coins on them as shown.

The aim is to remove eight of the coins and leave the ninth in the middle square.

To move, jump one coin over another to the vacant square beyond. Take off the coin you jumped over. Jumps can be in any direction: horizontal, vertical or diagonal.

Brainteaser solutions

Ages and ages

A. Simon is 3 now

B. Laura is 5 now

Leapfrog

One possibility is: Jump 5 over 8, 9, 3, 1 Four moves Jump 7 over 4 One move Jump 6 over 2 and 7 Two moves Jump 5 over 6 One move Total = 8 moves

* Encourage children to consider how to keep a record of the moves they are making so that they can report on their solutions without forgetting moves