High schooler knows test info, can explain subject matter well , appears very well prepared but info does not translate to paper on tests. Can someone offer insight into this?
Re: high school knows info but doesn't translate to tests
what jumps out at me in your post is that it does not translate in a written way. If your child knows the material and can reproduce it verbally or has performed better on verbal assignments it might be a case of NLD (non verbal learning difference).
Could it be related to test anxiety; or, could it be that the test is not provided in a way that student can demonstrate his/her mastry of a subject? Have you considered alternatives (e.g. for students who struggle with reading or writing sometimes the test can be read to them or they can provide oral responses)?