BBC Bitesize - all KS2 subjects

https://www.bbc.co.uk/bitesize/levels/zbr9wmn

Topmarks Searchbar - the website shares its own games, other websites (some mainly aimed at teachers and/or parents) and activities. Just look at the subject you are interested in!

https://www.topmarks.co.uk/Search.aspx?q=top%20marks

And... any search engine where if you ask the right question, with the right permission, there is a wealth of knowledge and fun to be found!