Good writing, apart from spelling and grammar, requires a wide vocabulary so that just the 'right' word is chosen to go into a sentence for the context in which it is written.
One of the hardest things is to understand when a word is right in a certain context and when some alternative taken, perhaps, from a thesaurus would be better. The exercises linked to here are all of the same kind, aiming to broaden the active vocabulary of students.
Eaach example sheet is a PDF file which prints as a single A4 sheet containing thirteen words to be considered. Below each word are five potential synonyms. In the earlier sheets, only one of the alternatives is a close synonym for some particular meaning of the word being considered. In later sheets two, three or even more could be synonyms - in different contexts.
These exercises are set first for some kind of homework and, in some subsequent lesson for active discussion of better/worse synonyms, shades of meaning, viable alternatives, etc.
These sheets are graded from easy to difficult as you get lower down the list!!