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.
After many of the Civil War battles, photographers took pictures of the mangled bodies waiting to be buried. Does this photograph depict an actual battlefield scene, or did the photographer contrive it?
See how African Americans faced numerous assaults upon their newly won political rights after the Civil War. What are the references employed by the cartoonist Thomas Nast in his cartoon, <em>This is a White Man's Government?</em>
In this cartoon, how does the artist use symbolism and humor to deride Parliament? See how anti-British political cartoons helped shape colonial attitudes towards British actions, like the Stamp Act of 1765.
The World's Columbian Exposition made a statement about the future of city life — a chance for something better than the squalid, polluted, and overcrowded industrial cities of the 19th century. What vision of the future city did the fair present?
This image of a steer skull seems straightforward, but it generated enormous controversy at the time. Can you imagine why? Hint: It was taken to document the hardships Americans suffered during the Depression.