Reading Eggs makes learning to read interesting and engaging for kids, with great online reading games and activities.
https://www.topmarks.co.uk/ Maths skills for KS2
https://www.bbc.com/bitesize/subjects/z826n39 BBC Bitesize
http://mathszone.co.uk/ Maths zone
http://www.crickweb.co.uk/ks2numeracy.html Crickweb free online maths games (needs Adobe Flash player)
https://www.topmarks.co.uk/english-games/7-11-years/spelling-and-grammar English quizes from Top Marks