https://github.com/LambdaSchool/react-stateful-widgets/blob/51e2cb366bd1e1a83c50f60856a5dc93e3d05ce2/src/components/Squares.js#L55
I've observed a lot of students get stuck with a bug that is produced by the code above.
It should be:
className={`square ${getClassName(id)}`}
A lot of the students complete the assignment, but then don't notice that the class name evaluates to squareactive when it should be square active