Junior Image Bank

Sources

Paid for stuff is available here:  https://www.123rf.com/ There is a lot of it and the quality is high. It is effectively £2.28 per image.

Free stuff (public domain) is available here: https://openclipart.org/

Stuff that is free to use but is not public domain i.e. requires you to credit the author and reference the licence is avaialble here: https://commons.wikimedia.org/wiki/Main_Page
There is also a small amount of public domain stuff here, though the quality is patchy.

Stuff we already have

Stuff we already have includes:

Congratulations etc

Pieces

Christmas

Kids playing chess

Good Luck