First, choose an infinitely long list of denominators. This could be anything you want: all odd numbers, all numbers that are multiples of 10, or the infinite list of prime numbers. Second, for each ...

When my students grow too dependent on their calculators, I ask them to find a number that, when multiplied by itself, gives them 2. Students quickly see that since 1² = 1 and 2² = 4, the answer has ...

Infants and animals are able to understand approximate quantities of different types, in terms of relative proportions of the numbers of different sets of objects, provided the difference in numbers ...