Just a general recommendation: for math/physics/CS it's far more useful to work through problems than memorize facts. I'll use linear algebra as an example since that shows up often in your cards.

Say you want to learn about eigenvectors and eigenvalues. Instead of writing the definition, you might have a card which asks the following:

"Create a matrix whose eigenvectors or eigenvalues are always equal."

This will force you to do two things. First, you will learn from creating the card since you're forced to synthesize the information rather than copy. Second, your recall will force you to work through this newly created problem.

Another general strategy is to just pick a problem from a book that uses the concept. If you ever get the problem wrong, you oblige yourself to solving an additional related problem from the same book (i.e. find the basis of one of the following matrices).

I guarantee you will learn 10x more effectively.

Also beware of falling victim to spending more time on building tools than learning... I've found that pencil and paper go a lot farther than people give credit.