There's still time before school (and early bedtimes) start up again — take advantage of balmy evenings to spark an interest in astronomy.
Here's a great free download that uses a deck of playing cards to introduce you to the night's sky's constellations in a fun, entertaining way.
Sundials are amazingly simple yet effective devices. They range from sticks planted in the ground to precision-machined marvels costing thousands of dollars. The design shown here can be constructed in minutes from materials lying around your house, but it's surprisingly accurate.