You could ask her to build a trebuchet and explain why she built it the way she did. There's lots of online resources for that and it doesn't have to be too mat

You could ask her to build a trebuchet and explain why she built it the way she did. There's lots of online resources for that and it doesn't have to be too math heavy if she isn't yet studying F=ma, potential energy, kinetic energy, etc. And if she is far enough along to know/learn those things then they can be applied to. Hope this helps