Encouraging students to use critical thinking is more than an extension activity in science and math lessons, it is the basis of true learning.
Teaching students how to think critically helps them move beyond basic comprehension and rote memorization. They shift to a new level of increased awareness when calculating, analyzing, problem solving, and evaluating.
Learning algebra is difficult for most students. Ask any student what they are learning in algebra and you will probably receive an answer similar to this (after - Why do I need to know this?).
"Using Xs and Ys a lot, a bunch of numbers and symbols, and memorizing a lot of rules."
This often comes with learning algebra without connection to anything students can relate to. When students learn basic math, they can make a lot of connections.