Stage: 2 Challenge Level: 
When will the first light flash?
When will the second light flash?
So when will they flash together?
Could you predict when they would next flash together? How?
When will the second light flash?
So when will they flash together?
Could you predict when they would next flash together? How?
Working systematically. Multiplication & division. Addition & subtraction. Divisibility. 100 square. Interactivities. Factors and multiples. Odd and even numbers. Properties of numbers. Generalising.
Published September 2000.
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