Worked example: act
ACT is the base. ACTION is a noun, ACTIVE is an adjective, ACTIVELY is an adverb, and REACT is a verb with a prefix. Comparing sentence roles shows why related spelling does not make the forms interchangeable.
Base idea
Start from the shared form and meaning.
Added part
Name the prefix or suffix and visible spelling change.
Sentence role
Check whether the result acts as a noun, verb, adjective, or adverb.
Build a family map
Place the base in the center and label every branch by part of speech and spelling change. Then write one sentence for each form. This makes derivation visible while avoiding the claim that every similar-looking word belongs to the same historical family.
Check the sentence role
Take one family and leave a blank in three sentences that require different parts of speech. Predict the needed form from the sentence structure before checking the spelling. The exercise connects morphology to use rather than rewarding a list memorized without context.