Usually this is important for things like depth perception, but occasionally it leads us astray. The cues deceive us into thinking we see something that isn't true, or isn't even there. Great explanations and a wonderful links section add depth to this site, whose creators describe as a cross between an online encyclopedia and a portal. Dr. Gregory is a good friend of the Exploratorium and director of The Exploratory Hands On Science Museum in Bristol, England. Although the site promises explanations at both an introductory and advanced level, only the advanced section was available during my visit.
Favorite clicks are the numerous interactive illusions.
Sand Lot Science has over one hundred online exhibits. Here is a familiar word with the top half missing. Place your mouse over the top half of the word. Now the bottom half goes away. Before you begin your project, you'll need a good understanding of the scientific method.