For a school project, my son's building something which requires that he use
curved wooden "rods". Not really rods, but 1/4" square bar stock (best term
I can think of). A friend had a lot of wood left over from a project, and
donated it. There are two types: Balsa, and one which the friend believes is
basswood. So...my son got on the web and did some research on steam bending
wood. Most sites he found said 10 minutes of intense steam should do the
trick. He build a jig using nails, to hold the steamed wood in shape after
steaming, and arranged a couple of wide pots with lids so the wood could sit
on the rims of the pots, but be covered, and thus bathed in steam.

Within seconds of being removed from the steam, the wood was moved to the
jig. 4 hours later, took the wood out of the jig, and it sprang back about
halfway to its original shape.

Is there a something he's missed here?

The final shape needed is this: Each 2 foot piece of stock has to look like
1/4 of a circle after bending.