Practice classification/pattern recognition skills by guessing which button out of sixteen the computer has chosen. Go through a series of online questions about the buttons that differ in size, color, shape and number of holes to determine the answer.
Many sources of hazardous waste can be found in your own home and require special disposal. Can you determine which household items are hazardous, which can be recycled, which go out with regular household trash/garbage and which should be washed down the drain?
Try to judge when you think a minute has passed without counting in your head or watching a clock. Use the online stopwatch to record your guesses, get some friends to guess as well and try to come up with reasons for the variations in responses.
How many valentines are exchanged if each of five friends gives a valentine to each of their other friends? Reflect on your solution, compare it with some others listed, and think about how you would solve a similar problem for more people.
Discover a fourth spatial dimension by using analogies (point, line and plane) from lower dimensions. Model objects of lower dimensions to gain understanding of a hypercube, which exists in the fourth dimension.
You took four snapshots of some geometric shapes that you saw on your train trip around a circular track. You dropped the pictures and got them mixed up, and now you must imagine your trip to put them back in order.