Are You Setting Your Students Up to Fail on Gas Laws?
You are walking around your class passing out graded gas law tests. Most of the students are keeping tests face down. You can hear some of the students suck their breath in as they see their grades.
What happened? You worked example problems. You explained the steps to the problems. They did their homework.
After using an entire red pen grading 135 tests, you are wondering what you did wrong. And asking if your students studied at all.
Instead of blaming yourself or the students. Consider the typical teaching method put forth by the many textbooks along with the provided tests.
Is there something missing? A step that you skip because it comes so easily to you?
Let me explain.
How We Teach Gas Laws
Chemistry comes so easily to us. Often we don’t realize we need to break some concepts down way more than we think we should for our students. Sometimes that happens when we teach gas laws.
When we teach gas laws we start with Boyle's Law. Why? Because it has the easiest mathematical formula.
Then we do a few example problems for Boyle's law on the board or through PowerPoint.
Often we’ll mention Boyle's Law has an inverse relationship. Then, we give students a worksheet on Boyle's law for homework.
Next, we do the same thing with Charles law, Gay-Lussac, and the ideal gas law.
There’s really nothing wrong with those steps or teaching the laws in that order. But, if you look at a few textbooks or curriculums, you’ll see a lot of math.
If you increase the pressure, what happens to the temperature of the vessel? If the size of the container decreases by half, then…
This isn’t something I used to talk about in class a lot. But it’s important. (Especially, if you have a future engineering student who will eventually work on reactor vessels.)
Which brings us to the question:
Does That Way Work?
The textbooks we've used have trained us to go through the lesson emphasizing the math. Teaching the math is an important part of the lesson. But it’s only a part of the whole lesson.
The time spent on math vs concepts is unbalanced. Look at old notes or a textbook.
How much time is spent going over math problems? How much of the test is over math problems? How much time is spent going over word problems and relationships? How much time is spent helping students understand the math?
What is the goal of your lesson? Do you want your students to be able to solve gas law math problems? Do you want to emphasize the concepts?
Consider your students’ academic background, if they are headed to college, state standards, and your goals for them while making this decision.
Changes We Should Make
We don't want to hand the test to the students. But you do want to mold their thinking processes, right? You want them to be able to evaluate those inverse and direct relationships. So talk through scenarios and use demonstrations. (Use doodle notes, an Instapot, spray paint can, etc.)
If we never give students the opportunity to evaluate what happens when pressure increases, then they will bomb those questions on the test.
We can't just go over how the relationships work with one of the gas laws and ask students to apply it to the other laws. (I know you’d never do this, but I did!). So, if you don't go over math problems and relationships strategically, students will obliterate the application part of the test.
Go back over your notes. See how much time you want to spend on math vs. word problems. Then, look at your test and see if the ratio is right.
I kept this in mind when writing my doodle notes. Each page has a scenario where the gas law relationship has to be thought through—not just solved. Students will have to think through how increasing in one variable will decrease another variable.
And that's where students get stuck. But not after you teach the lesson from both the math and conceptual perspective.
Want Pages That Illustrate the Math and Concepts?
Go to my store and buy the doodle notes. There are 6 pages that make teaching this lesson easier. There is a page that covers each gas law with specific details for concept learning.
In addition there are 2 pages that help your students learn how to set up and solve word problems.