Teaching critical thinking skills
I feel my most important job as a college professor is to teach critical thinking skills, not to teach complex one-use algorithms to students. The students I teach in my General Chemistry class want to go on to become doctors, pharmacists, engineers, etc. They need the skills to look at a problem, know what information they have, and solve the problem. My job is not to teach them the content of general chemistry, because unless they are going on to be professional chemists (almost none of them are) in 5 years, they will have forgotten 90% of the content I teach them. Do we honestly believe that those students who gets A’s in our class remember all of that stuff? They do not need practice in recognizing a system as ‘just like that problem I did in college’ and then solving it. They need practice in true critical thinking involving never-seen-before problems.
If we truly believe that critical thinking is what we want to teach students, then let us teach and test that, not memorizing a set of algorithm or a bunch of not too useful tables of information (10 different metric prefixes, every single chemical symbol, all the exceptions to every rule we teach, what oxidation state REALLY means, etc.). I have told many classes that what I am doing is teaching them how to think, and using chemistry ideas and concepts as my tool. I know they will forget the content, I just have to accept that, which is tough.
My exams contain questions that the students have never seen before. They are slight variations of problems done in class, but involve multiple concepts in one question. If the students understand the base concepts (as taught in class) then they should be able to manipulate that knowledge to solve my (previously unseen) problem. My exams are tough, I want them that way.
When we work on complex, multi-step calculations, I try to teach them to come up with a ‘plan’ first. For example, I might have a problem that states “Magnesium metal reacts with hydrochloric acid to form hydrogen gas and aqueous magnesium chloride. If I have 3.0 g of magnesium metal, how many mL of 6.0 M HCl must I add to completely react the magnesium?” Now, in my mind, coming up with the plan “g Mg -> mol Mg -> mol HCL -> V HCl” is all I really want them to do. Once they have that plan figured out (which is the hardest part for them) the rest is just plugging numbers into the equation and their calculator. They have plenty of practice using their calculator from math class, so why work that skill? That’s easy, why test it?
Well, ok, exam time comes and the students freak out. They get test anxiety and get flustered easily and start making the problems harder than they really are. I want to reduce that negative reaction on exam day. What I really want is to give them time to think about the problem beforehand. I think I might have come up with a solution.
What if, 3 days before the exam, they saw this on my website:
1. XXX metal reacts with YYYY to form ZZZ and AAA. If I have 3.0 g of XXX, how many mL of 6.0 M YYYY must I add to completely react the XXX?”
There lies nothing but the root of the problem. There is not enough for the person to pound out the calculation. (well maybe a sample if they put numbers in) There is way too much unknown. What they can do, however, is struggle (and study?) how to do that problem. They come up with the procedure, but can’t do the problem. Great.
Understand that I want student who studied and learned the concepts to get 90+% of the points available. I want the students who don’t care or study to do poorly. It might sound crass, but I have a job to do as a General Chemistry professor. If you cannot succeed in my class, you will never move on to become a doctor, engineer, or pharmacist. Sorry. The students who want to be successful (the smart ones as well as those middle group who just have test anxiety) will study these partial problems and get the plan down so they will do well on the exam. Those who don’t study will do poorly, as usual. Perfect. Since I am giving them ‘most’ of the exam early, I can ask slightly harder questions. I of course will not help them with these partial problems beforehand (defeats the purpose)
I gave my first exam today and the students did what I expected, made it harder than it was. I think I will try this before my next exam.