In school, in theory, the class is supposed to teach us about MOA then we will have background to remember the drug. But, in reality, often, we got tested on drug before the class taught us anyway. So, we learned by self studying.
We don't have to know all details of MOA and how it works, we need to know just basic MOA.
For example,
amlodipine: basic MOA is Calcium Channel Blocker. If you really want to wonder about Calcium Channel Blocker, then, you can read more or watch youtube or get the class.
Lisinopril: basic MOA is ACE inhibitor. If you really want to wonder about ACE inhibitor, then, you can read more or watch youtube or get the class.
Atenolol: basic MOA is Beta Blocker.
The sites that are free and helpful for me during pharmacy school are:
www.rxlist.com
www.drug.com
www.wikipedia.com (nice and surprisingly, you see right away the basic MOA with wikipedia, as presented at this link (while RXLIST.com OR DRUGS.COM did not):
http://en.wikipedia.org/wiki/Amlodipine#Mechanism_of_action
Good luck...If you need tricks to memorize the color of Synthoid or color of Coumadin quickly and efficiently, let me know, I may find it in my computer somewhere out there...