Sources of good questions

Altering the numbers in a problem has an effect on the strategies that are preferred.

You can manipulate the numbers to see if students adjust their preferred strategy to suit the problem.

To find out which strategies are best for solving a problem, solve it yourself, then try using other strategies.

Varying the context of the problem also has a pronounced effect on difficulty.

In general, problems that tell of an action are easier to solve than others where the action must be inferred.

For example, difference problems tend to be harder than take away problems. Result unknown problems are usually easier than change or start unknown problems.

Here are some sources of good questions you can use for interviews.

• The New South Wales Department of Education has examples of methods used in mental computation.
• The Victorian Department of Education and Early Childhood Development has a number of teaching resources for mental computation.
• The Early Numeracy Research Project's Mathematics Online Interview also contains mental arithmetic questions.
• New Zealand Maths provides GloSS interviews which contain good questions for mental computation that span a wide range of difficulty.