So average atomic mass can be kinda tough to teach, especially to kids who don’t have the strongest math skills. Considering I was one of those kids, I know how hard it can be to learn science when the math isn’t where you’d like it to be. I always do my best to teach my students the math that they need in a way that even the “not so strong in math” kids can get it. I teach it the way I needed to be taught as a “not so strong in math” kid. And of course, I have a favorite great average atomic mass activity. In fact I have two. First, I teach it in terms of their report cards!
Average Atomic Mass Activity for the Classroom
You and I know that if tests are worth 50% of your overall grade, you would take your test average and multiply that by .50. That’s how much the tests contribute to your grade out of 100. The closer to 50 the better! My “not so strong in math” students don’t always get that right off the bat. The problem is that they don’t understand the difference between a straight average and a weighted average. And then their math deficiencies can cause issues in their science learning. The kids grow frustrated by this, and so do I!
So I create a scenario where the online grading system is down and all the teachers need to calculate their grades for the students. It’s up to the students to “help” the teachers. In doing this, the students calculate category averages, which are straight averages. Then they calculate overall averages, where I get to teach them the difference.
For the kids who REALLY struggle, I usually use a pie chart to do it. I’ve even explained it using flavors. If a milkshake is 50% banana, 20% chocolate and 30% peanut butter, what does the milkshake taste like? What if it were 90% peanut butter? The get to evaluate how percentages CHANGE the overall flavor of the milkshake. These kids are usually taken to the side and taught solo in or in small groups.
I really like this average atomic mass activity because it gives a real life connection to the concept of weighted average, and it is something that every student in my classroom can immediately relate to.
Average Atomic Mass Lab Activity
The next day we will move into a lab (another food lab that is.) I’ve done it with dried beans, which I’m really not a fan of. I have also done this lab with marshmallows, but I think I’m going to move on to pretzels. Basically you give the kids a sample of “beanium” or “candium” where the different weighted types of beans represent a percentage of the naturally occurring isotopes of that element. Once the kids get to SEE the isotopes, and how they represent different amounts of the population and they actually make the manipulations themselves, it clicks. I like to do this with food of course, because it makes it more fun.
It’s important to do these calculations yourself and make sure that the “isotopes” you select round appropriately so that the math makes sense. Unfortunately for me, I made this mistake, and included hot cocoa marshmallows that rounded down to a mass number of 0. Boo! Don’t let my mistake be your mistake! You can get a copy of my lab rubric by signing up with your email. This rubric includes sentence starters that really help my students to properly communicate their ideas. It also helps them to uncover what they learned very well.
You can check out both of my average atomic mass activities here!
