Anyway... I was talking about word families; by which I mean words with the same ending sound and spelling. I think of rain, pain, brain, chain, train and stain as belonging to the same word family.
I like using word families to help learners get in the habit of cueing off the initial consonant or blend sounds. This provides a nice counter-balance to "meaning-focused" readers who have trouble, for example, deciding between jacket and coat.
One of my favourite tools, when working with a small group, is the Upwords game. In this 3-d scrabble-like game, one player can spell out pain with their tiles, and the second can then place an r on the p to change it to rain, after which a third adds a t on front for train... and off you go.
But there have been lots of times when I've just asked learners to make lists of rhyming words (for that is also what these are). Or, I've made a list, and asked learners to read it.
The thing about this exercise, the hitch - other than the obvious problem of presenting words in isolation - is that it depends on a strong oral vocabulary.
It's much harder to get anywhere if the learner always has to ask "Is j-a-i-n a word?" or "Is w-a-i-n a word?" And things get even more complicated when you have to say, "Well, I think wain is an old English word for wagon, which we still see in the form of wainwright which means something like 'wagon technician'. And 'Charles' Wain' is what some Europeans call the group of stars we know as the Big Dipper... Do you know what the Big Dipper is? No? It's that group of stars in the north...."
Well, you can see how it can all go astray.
So... a useful tool. Sometimes.