Coach Wayne - I'm ordering your video but in the meantime here is our problem...My 8 year old daughter has "almost" had her backhandspring for months, but continues to not lock her arms straight so she "crashes" her head. Obviously this is dangerous and limits the surfaces she can practice on. Do you think it is a question of form or strength, and what can we do to correct the problem. She has joined a competitive cheer squad and desperately wants to master this skill! Looking forward to your help.

Most likely it's a question of FORM.
But remember... it's form in MOTION... which requires coordinated strength. The handstand position will help her acclimate herself to bearing a weight-load on her arms in proper form.

Get her against a wall into her handstand position EVERY DAY. Like... 20 repetitions of 10 seconds... each day.
She should demonstrate a straight line handstand from wrists to toes... leaning against the wall. NOTHING should be bent unless REQUESTED.
Intermixed with static handstands you should also request that she do slight handstand pushups. She only needs to flex the elbows and shoulders slight... then push straight and tall again.

The handstand is the vital position because the handSPRING passes through the handSTAND position. After she's done a hundred or so... remind her that she's passing THROUGH that position as she performs her handSPRING.

~CW