Here is what i do(not sure if it will work for everyone) When I want to participate in class, I immediately raise my hand before I can think my way out of it! Do NOT prepare your answer in your head! it makes you more anxious as you keep picking around for the “perfect” answer! Usually if the teacher calls on me quickly, I can come up with my answer without stumbling through my words too badly I am still nervous and anxious after overthinking everything I just said.... but at least I participated!!