In your metrics sheet, you will also be keeping track of:
How much you use these areas will depend on whether you have an all-inclusive fee structure or have students purchase their own materials. Even if they do buy their own, though, you probably spend some money on teacher reference books or printing for students so it’s important to track those too.
Keeping all of this in your sheet will enable you to see what you’re using the most and to keep items “in stock” if you use them regularly. It can also help you keep a tighter rein on your expenses if you tend to go over-the-top with book shopping!