Chrome Music Lab
There are lots of fun sound and music experiments on this site to try out. The Kadinsky is particularly fun for the whole family - make sure to try making a circle and see what happens ;) 

Online Virtual Piano

Classics For Kids is full of Games and Activities for all ages!

Check out the New York Philharmonic KidZone for some fun games and music challenges!

Bomomo
A digital Art generator which allows you to experiment and create fun Abstract art. There are no rules here! Just have fun, experiment, and see what you come up with!

Google Arts and Culture:
Packed full of fun activities for the whole family, from virtual museum tours, super up-close looks at famous paintings, and fun at home activities.

Jamboard!

Google's Virtual Whiteboard. Use this site/app on any device to doodle, draw, or create a diagram. 

Silk - Interactive Generative Art Program
Super fun for the whole family - create stunning visual effects and artwork with this simple to use program that has several settings allowing for a wide variety of images.