Do you know about a technique called Imagery? This is an method where in you imagine theory to picture. You visualise what you read. For example, if you read about rainbow, you need to imagine a rainbow in VIBGYOR colours. And you read everything in detail about it and picturise the same. So when you have to answer something about a rainbow, you remember the picture and you put it forth. This is a successful technique. You may as well give it a try.