Name the rule behind the error
Look for the first incorrect choice in your solution. Write the rule that would have corrected it and record the source location. If your notes do not settle whether the step was valid, ask for clarification before building more questions around that interpretation.
Change one feature and check the solution yourself
Swap the numbers or change the setting while keeping the decision that caused the error. Solve the new problem without looking at the old answer, then check the result against the source or a known worked example. If the new version needs an additional rule, use that version later.
Test the boundary after the first variation
Once you can do a close variation, change a condition that affects how the rule should be applied. Ask for a short explanation of the decision. Save this version for a later session so you have a fresh way to see whether the reasoning holds.
Worked example
You found the median before ordering the list. First try another unsorted list with five numbers and show the sorted order. Later, use six numbers and explain which two positions determine the median. The second version changes one feature, the number of observations, so you have to adapt the procedure.
Before you finish
- Link the new question to a specific rule and source.
- Change one important condition at a time.
- Check the answer independently before using the question.