I buy this as a much need tool in my classroom . we raise we own money since we be not give anything -lrb- thanks to the economy -rrb- . anyway , I be a bit disappointed because you have to turn off all the light and close the blind -lrb- which make it impossible for my student to see they papers to follow along . I guess I learn my lesson not to go for the least expensive item as you get what you pay for .