what are rule words?

Hi, my son and I are trying to do his homework. He needs seven rule words. Can you tell me what are rule words? Does it mean words with rule as a suffix maybe?

[Philly]

.
I really have no idea what "rule words" are supposed to be.
Just a guess: maybe your son is supposed to write seven words that come from the word 'rule'?
In other words: rules, ruler, ruling, ruled, unruled, unruly, rulable, self-rule
.
Or maybe your son's teacher wants synonyms for the word 'rule'...

[Tdol]

'Rule words' can mean words that are spelt the way they sound but have a rule that is applied to them, such as doubling a letter, like 'run' becoming 'running', or dropping a letter, 'like' losing the -e to become 'liking'.

You'll find some details on this here:
http://www.ldanh.org/docs/spellinginstrucion.pdf