Some of your kid's teachers encourage memorization of material but you do not agree because you think memorization is the lowest form of learning so what should you do?

Memorization is a low level learning skill that is important to have for some subject matter so that the higher level skills can be learned. Stressing the child out and working too hard and long on it though will work against learning.

A good example is learning math facts (addition, subtraction, multiplication facts) so that the "thinking power" can concentrate on the equations, division and other processes of mathematics. The easiest way to do this is to have a stack of cards with the facts and run through them nightly right before bed. Don't get too serious about it--just flip and answer as fast as possible--and put the missed ones together for the next night to answer first. This works if you do it consistently, because biologically our minds remember stuff learned just before sleeping.

Spelling goes the same way, but I think writing the Words several times each day should do the trick, because the questions will be verbally given and then written. For other things, like social studies and so on, the key is to do the homework properly so that the study materials are correct. Tests will go okay if the child has a good dinner and a decent bedtime (no phones, TV) the night before as well as a pleasant morning before school.