The Problem: Students can't tell the difference in superscripts and subscripts when they learn to balance equations.
My solution is to teach this topic visually!
When I first started teaching, I'd look at the book that I was teaching out of and cut out several examples. My thought was that I would save time because once I had shown them the concept they should be fine, right?
Not so right.
Each of the examples in a book or lesson plan is usually teaching a different nuance of the topic. Once I realized that, I tried to accentuate that to my student by saying, "This example is an example of when you have this situation."
So, when I teach balancing chemical equations, I start by showing them a simple balanced equation. Then, we go though and count each atom type.
Then I show them an unbalanced equation.
We go through and count up each type of atom and they see that it is not balanced. Then I ask them how would we go about fixing this.
Usually a student suggests changing the subscript and at that point I draw this out to the side. I explain how the 2 subscript is explaining that the hydrogens come as a pair.
Next I ask what would happen if we had two of the NH3 Molecules instead of 1. First, I draw it. THEN I write it.
They usually see that the Nitrogens are now balanced and the hydrogens are not. I ask them how we could use math to turn 2 hydrogens into 6.
We usually get to an answer of 3 sets of 2 pairs of hydrogens. At this point I have them count on their papers and tell me if it is balanced.
The last thing I do is I write out the equation again with subscripts one color and superscripts another color. This leads us into the point that superscripts and subscripts are different and you can't just change superscripts into whatever you want.
Superscripts do not have Superpowers!
Hope that helps. If you'd like the free worksheet that goes along with this click here. There is a more involved($3) worksheet that is 3 pages and differentiated in levels here.
Hi! I'm CoScine Creative. I have developed and run a tutoring center at a small college. I also teach some of their algebra and chemistry courses. And I will neither confirm nor deny pranking my students by pretending to be one.