# The Secret Formula for Fighting Fires

August 5, 2020

Firefighters get hot, but they may be the coolest heroes out there. Not only do these brave people save other people’s lives, but they need to do math to face the danger. When we at Bedtime Math talked to firefighter Joe Spych, he told us a secret about fire hydrants: the color tells you how fast they pump water. In one set of towns, a red cap color means the hydrant pumps less than 500 gallons per minute (GPM), orange means between 500-999 GPM, green means 1000-1499 GPM, and blue gushes out 1500 GPM or more. This matters because you need a gallon of water to put out every 3 square feet that’s on fire. By the way, a hose spraying 300 gallons of water a minute can fill about 8 bathtubs at once! But let’s see how much fire it can put out.

Wee ones: Plug your sink, then turn on the water and count to 10. Turn it off. Is the sink a little full, halfway full, or mostly full?

Little kids: If a fire truck has 5 “attack lines” (hoses) and you hook on 1 more, how many lines does it have now?  Bonus: Which pumps water faster, a red hydrant at 90 gallons per minute, or an orange hydrant at 600 gallons per minute?

Big kids: If a rug that’s 10 feet wide and 9 feet long is on fire, how many square feet is that? (Imagine 10 rows of 1-foot-wide squares, with 9 squares in each row.)  Bonus: If a gallon of water can put out 3 square feet of fire, how many gallons do you need to put out that fire?