This homemade hourglass can help your child visualize how little time she has before the school bus comes.

Pour colored sand into one bottle. On top, place a two-hole button that's large enough to cover the bottle opening. Add the second bottle as shown, and wrap the juncture securely with several layers of clear tape.
Use a clock to figure out how much time your hourglass measures (ours is about 10 minutes). To adjust the time, peel off the tape, add or remove sand, then replace the tape and time it again.