STEP 6: Overloading anything is a bad idea. Planes crash. Ships sink. Significant others run screaming from the home office. So Peter says that when your space reaches capacity, it's the one in, one out rule: If you buy a new book, out goes an old one. When, like Joanna, you discover a trove of pens or blank CDs, you can donate them to a school (Donorschoose.org). The average teacher spends $659 of her own money on supplies and will be grateful for your castoffs.