These are resources which we have found to be helpful for cyclists of all skill levels!
In particular, here are 4 videos which the League of American Bicyclists highly recommend.
Kid safety: NHTSA Bike Safe, Bike Smart
General safety for adults: Cyclist’s Eye View Part 1
General safety for adults: Cyclist’s Eye View Part 2
More safety:League of Illinois Bicyclists motorist share the road for motorists