We all love water squirters to spray our friends. Well, nature wants to play, too. A “geyser” is a burst of underground water that shoots up through the ground. The famous geyser Old Faithful in Yellowstone National Park “erupts” exactly every 91 minutes, shooting boiling hot water and steam 185 feet into the air for up to 5 minutes at a time! In the old days, people tried to use Old Faithful to wash their clothes. But we think water fights are more fun than doing the laundry.

*Wee ones:* If the boiling water has been spraying for 4 minutes and then sprays 1 more minute, for how long will it spray in total?

*Little kids:* If Old Faithful is about to start spraying in 10 seconds, what numbers do you say to count down, starting with 10? *Bonus:* The water sprays 185 feet into the air. Is that closer in height to a person or a 12-story building?

*Big kids:* If an eruption ends at 3:10 pm, at what time will you see the next one if it starts 91 minutes after that? (Reminder: there are 60 minutes in an hour.) *Bonus:* If people try to wash their laundry at Old Faithful every 3rd day starting on a Monday, how many days later will they get to wash laundry on a Tuesday?

Answers:

*Wee ones:* 5 minutes.

*Little kids:* 10, 9, 8, 7, 6, 5, 4, 3, 2, 1. *Bonus:* The 12-story building.

*Big kids:* 4:41 pm, since the first 60 minutes will bring you to 4:10 pm. *Bonus:* 15 days later. You need a Tuesday that is a multiple of 3 from Monday; the next day is 1 day, the following Tuesday is 8 days, and the Tuesday after that is finally 15 days (2 weeks 1 day).