Common Homonyms in English
Part of the Teaching Kids to Spell For Dummies Cheat Sheet
Homonyms are words that sound the same but spelled differently. English contains dozens of homonyms, but the ones listed below are the most common of all. Your child is bound to grapple with some or all of them at some point, so if you help him in advance, you can make his efforts more productive and less frustrating.
there, their, they're
to, too, two
threw, through (you may want to look at thought here too)