Variation theory in mathematics education

How might variation theory affect mathematics teaching and learning?

Variation theory (VT) is a way of analysing and planning teaching and learning activities which focuses on what changes and what stays the same and the effect this might have
Researchers suggest different emphases for different critical aspects when structuring variation in maths lessons, but recommend that students should see difference before sameness, including counter- or non-examples
Well-structured tasks are important, but successful use of VT also requires teachers to be effective in using these tasks to direct pupil attention
Using VT can be a way of helping maths teachers develop professionally, but may also formally characterise what they are already doing
Teachers should make sure they select and use examples very carefully as a way of drawing attention to mathematical structure
Professional development that increases maths teacher expertise in example and problem choice may be particularly beneficial