Equation Balancing Sheet

So I like the idea of a spreadsheet that students can use by themselves, without a teacher around, to practice a skill and check their answers. With that being said, I created an Equation Balancing Sheet in Google Sheets, so that students can practice balancing equations:
https://docs.google.com/a/isd622.org/spreadsheets/d/1hOZrpN9TlfmQPSg8W9p2ohpju6U7dW105mMtYxusttk/edit?usp=sharing

How it works:

1. The boxes in yellow are where potential coefficients will go. It will not accept a 0 or a 1 for a coefficient (data validation accomplishes this). 
2. When all of the coefficients for the equation have been entered, you select "yes" from the drop-down box. If the coefficients they entered match the coefficients I balanced myself (which are present in columns V-Z, though they are obviously hidden), the equation will turn green to indicate that they have it right. The equation will NOT turn green until they select the "check answers" box. The reason for the box is that I don't want the equation to 'magically' tell them they have it right the moment the correct numbers are entered (that might stop them from doing the counts themselves).
3. They also need to fill in what type of reaction they have on the right side (Synthesis, Decomposition, Single-Displacement, Double-Displacement, Combustion) from the drop down arrow. If their answer matches my answer, it turns green. Otherwise, it turns red. 

Note: this isn't good for a homework assignment for points for a student. Why not? Its super easy to hack. And by 'hack', I mean 'unhide the cells with the answers'. Its meant to be a way for the students to practice their skills and be able to get instant feedback if they are right or not. If they're cheating on this, well, they're really only cheating themselves.

Any feedback on this is welcome - its an idea that popped into my head the other day and I threw it together in short order. I'd especially love feedback from my zero readers on how to improve the appearance of it.