When it comes to the exam -if it is soon I would concentrate on more traditional study techniques. Photoread the text, then use traditional study techniques as activation.
I believe that it would be more useful to learn school/university subjects and photoreading separately.
First learn photoreading on lighter material, then apply it to the heavier texts.
All of the activation methods are valid, and it is very much a matter of personal taste as to which you would prefer to use in any situation.
Maths and science activation would often involve quite a lot of working problems (at least in my case! Other people may have a different experience).
I like to use MindMaps in most activation, in addition to superreading and dipping.
The asking of questions is primeordeal to any activation, as those become the fly-paper that the information will stick to, and where you will find access to it later.
In any case: Play with it, enjoy the process - there really is nothing to lose, because if you find that you much prefer "regular reading", you can always go back to it!
All the best,
K.