This lesson is on the order of operations. Everything you learn in math is important but I would say mastering the order of operations is "extra" important to math students at this level. As a math teacher I have seen so many student errors due to the lack of really understanding the order of operations. Hence, you should pay extra attention to the lesson and follow the procedure called "PEMDAS". Don't be fooled into thinking this is easy because you can do a few basic problems you really need to practice more difficult problems to have absolute confidence in this area.