I used the following presentation to go over how and why to balance chemical equations with my 9th graders:
The concept itself isn't complex, but instruction often gets bogged down in providing students with a list of specific steps to follow (First, count the number of atoms, second...). Suddenly it goes from being a simple concept to a complex procedure which almost requires students to actually memorize the specific steps.
I started with a quick review of the Law of Conservation of Mass (matter cannot be created or destroyed, though it can be rearranged), and then jump into the teeter-totter analogy to explain why unbalanced equations violate this law. We then worked through some examples together.
With each repetition I increasingly withdrew my support. By the third example students could go through and balance equations without me around. They didn't need to follow a prescribed set of steps. They knew that you can''t have more oxygen atoms on one side of the reaction than the other and worked through to figure out the balanced equation.
As for technological savvy to create the edited images of the sign: I did all image editing in PowerPoint itself; which is to say it's pretty basic and pretty crude.