Donations to the classroom will help in purchasing consumable products. Much of science consumables used in class can be purchased at the local grocery or warehouse store. Unfortunately, budgets allow for a tiny portion to be allotted for local stores; the remainder comes out of the teacher's pocket.
Further, the adopted curricular material is foundational to the learning of science; however, building a unit requires adding to the curriculum to allow for all students to create a better picture of what the unit is comprised. The goal is to create a "Big" picture understanding of the unit (energy transformation--not limited to electricity--and how the transformation along with magnetism lends itself to motors, electricity generation, the electromagnetic spectrum). In order to build those big ideas/pictures/understanding, I need to supplement the curriculum with materials outside of the text with videos, readings, and lab experiences. Again much of the supplementation is funded by my pocket and not the school's already limited budget.