You've probably done a Google Image search before, but did you know that you can also filter the image results by color? Just scroll down on the image results page and choose the desired color from the color palette in the left hand column.
For example, if you wanted a picture of a red car, you could do an image search for the word "car" and then choose the red color box to see only red cars.
A good use of this for educational research would be to search for charts or graphs for a particular topic. Just do an image search for your topic and then choose the white color box. This works because most graphs or charts have a white background.
For example, if you want a diagram of a Tesla Coil, do an image search for the word "tesla coil" and then choose the white color box.
Regular image search for "tesla coil":
The same search filtered for the color white:
How have you used Google Image searches or color filters?