Kids grow like weeds, in wild, unpredictable ways with sudden stops and starts. Sometimes one part grows more than another. Sometimes they pop out all over at the same time. Nonetheless, grow they do, generally until some time around college. Or not.
Most of the time, you can get an idea of what size they’ll stop at by looking at your family, so that will give you an idea of the maximum size you should plan on buying for them. Are all the guys 5’10”? Or 6’5”? That will give you an idea of how big and tall your kids will end up.
1. Seasonal items (summer) – Even if the SHTF, the kids are going to find somewhere and want to go swimming (except maybe for Lisa in Arizona). For younger girls and boys, you can probably pick something in their favorite color and they’ll still like it well enough in a few years. Odds are pretty strongly against a teenage girl liking anything you choose for her a few years in advance, but if you buy it on sale or used cheap enough, you won’t need to stress about potential unused items, and at least she will have something new (or nearly new) to wear.
Don’t forget their entertainment, either. If you haven’t already, start buying toys that don’t need batteries but do need imagination – like Lego or art supplies (although you can run out of art supplies) – and on Board Games and other things your family can do if the power goes out. (Keeping a fully charged portable dvd player with a 12 hour battery on hand in case of short-term outages is nothing to sneeze at, either, in terms of prepping with kids.)
And remember, whatever it is you buy, they will probably swear they hate it and not want to have a darn thing to do with it. But like a weed, one day you will look up and notice they are now wearing it, playing with it, or eating it. Eventually.