The findings raise important questions about how this knowledge is learned, maintained and transmitted across generations, for example, by young chimpanzees observing and using their mothers' tools, and whether similar mechanical principles determine chimpanzees' selection of materials for making other foraging tools, such as those used for eating ants or harvesting honey.

Here's a video showing the process. I'm totally sharing it as informative content, not because it's cute. (Okay, it's both.) Check around 1:50 - child is trying to fish termites with a leaf, mum gently picks the leaf from the child's hand, drops it, and indicates a more appropriate tool.

I think that what's happening there is:

At the start, a chimp who never fished termites tries random stuff: large leaves, flexible sticks, rigid sticks etc. Some attempts will suck, some will be meh, some good. Based on success cases, the chimp generalises what a good termite fisher should be: long, thin, flexible. Next time they're going to fish termites, they'll prefer tools with those attributes, refining further their mental model.

This process is trial and error, so it takes a while. And the time spent is kind of a big deal for a growing child who needs protein. So the mum (or the parents? dunno if male chimps do this) shows good tools, either by example or by direct interference (as in the video).

So it isn't like the mum is teaching the child the "best" tool; that's part of the mental model, internalised by the chimp. Instead the mum is guiding the child to develop experiences that they can use to form that mental model.

This has huge implications for human kids. Granted, we have a better communication system than chimps do, but children aren't exactly experts in that system, so a lot of their learning should resemble how chimps do it. And more than that - perhaps we learn language itself in a similar fashion?