Why we can cancel or crossmultiply
Activity: Simplifying Rational Expressions using Equivalent Fractions
If you have taught Middle and High school, you will have no doubt witnessed students cancelling parts of expressions without understanding what they are doing. (I often accused them of "cancellitis"!) Also, they crossmultiply even when there is no equation.
This is likely a result of learning procedures that never made sense to them. At the very least, they don't know when to apply the proper procedure.
This activity can help to remediate the tendency to cancel or crossmultiply by returning students back to the basic idea of simplifying fractions.
This is likely a result of learning procedures that never made sense to them. At the very least, they don't know when to apply the proper procedure.
This activity can help to remediate the tendency to cancel or crossmultiply by returning students back to the basic idea of simplifying fractions.

