Physics / astronomy challenge / Olympiad

[Muu9]

Any know children planning on participating, or looking for resource recommendations?

Are you talking about the Physics Olympiad, OP?

The website bpho.org.uk has some good resources, particularly under the heading ipho.

The Institute of Physics has good explanations of topics, for secondary teachers, in the Education section of its website.

MIT has recorded videos of some of their most popular introductory course modules, freely available online. Many are accompanied by (old) problem sets and coursework tests, some with solutions. I bet there are some introductory Physics modules and possibly introductory Astronomy modules. I think this collection of material is called something like MIT Open CourseWare.

These are older and not necessarily terribly polished by modern standards. But the academic side is, needless to say, very sound.