The problem is that you are giving her techniques after she has blown up. You/she need to deal with this before she has erupted. If you can realize anger is coming on then you have a chance to deal with it. Its pretty tough to do when you are in the midst of an anger attack.
There are some good books aimed at this age group. A good example is linked below. Buy it, read it with her, practice the steps with her. Also on this link you will see several other suggested books that will be helpful. Remember, you are going to essentially help her brake a habit. It will not happen overnight. The link is
Hope this helps. Best wishes.
I agree that the best time to help provide coping skills is at the good moments. This is when she can listen. And acting them out with what you CAN do and CAN'T do (even making the can'ts funny helps) really can be impactful.
But this is a change in behavior for her. That makes me wonder what is going on. School more challenging? Kids being mean at school? At 10, she also may have hormones kicking in (good times). Opening communication about these things may help too. Is she a perfectionist by the way?
Ok thank you so much for your help!!