And of course eventually he will learn to read English in school, since Japanese schoolchildren do learn. But he will learn from someone whose English skill is far less than his own.
So I think that it is a challenge well worth our effort, Tofu's and mine, to keep working on English reading. My challenge is to make lessons that are fun, not too simplistic, that he will enjoy enough to look forward to--not dread--letters from Grandma. His challenge is to read them.
This particular rule, about how an "e" on the end of a word makes the vowel say its name, is one that he actually already knows. But occasionally he stumbles over it, and so I thought it was worthwhile to make a whole interesting lesson on the subject. Besides it was quite fun to find words that worked for this exercise.