Math
Khan Academy
https://www.khanacademy.org/
https://xtramath.org/#/home/index
http://www.abcya.com/
Reading/Phonics
Have your child read and take a quiz using RAZKids
www.raz-kids.com/
Spelling and Writing
https://www.spellingcity.com/users/1NRES
http://www.abcya.com/
Just for fun:
http://www.education.com/activity/article/fox-in-sox-tongue-twister/
http://www.starfall.com/