Bicycle Math

What You Need:

• Road map of your community
• Ruler
• Bike
• Kid with helmet (and some energy to burn)
• Watch with second hand (stopwatch is even better)
• Pen and paper

What You Do:

1. Pull out an old fashioned paper road map of your community. (Note: this may seem obvious, but with today's GPS systems and mapquest options, it's not! You can usually find maps at a local gas station or a AAA office, or you can download one. No matter what, make sure it's something you can spread out, look at, and write on.)
2. Review the map legend with your third grader, and make sure he understands major symbols as well as measurements to scale.
3. Together, mark out a common, safe route that he'd like to ride with you. Use a highlighter to mark it, and then calculate: how long is this route? In some communities, this may be a bike trail; or perhaps a bike path marked off on a street; it may even be a regular route to school. In any case, mark off one mile.
4. Now get ready to ride, and be sure to bring your watch along, too. When you get to the starting point for your mile, start your stopwatch; click it off when you've passed your “finish” line, and round to the nearest ten or fifteen minutes.
5. When you're back home, you'll now have time and distance for your ride. So here's the adventure: how many miles per hour did you go? Parents, beware: this can be tricky, and you should plan to help. Furthermore, this is math that third graders usually won't understand well until the second half of the year. Once they get it, though, they're off!
6. Here's what to do: start by writing down your time and distance at the top of a plain page. On its face, this is easy: your child took a certain amount of time—let's say 15 minutes—to go one mile.
7. But here's the challenge: how many miles per hour is this?
8. To reinforce third grade fractions, start by turning the minutes into a fraction of an hour: ¼. Then explain to your child: we know that you could go a mile in ¼ of an hour. How many miles could you go if you could keep going 4 times as long—one full hour? If your child stumbles, pull out the map and see if you can figure it out by tracing a route.
9. In our example, a third grader rode at 4 miles per hour. Try making a chart and putting it on the fridge. Can he beat this time?
10. Don't be surprised, of course, if your third grader notices that a car can take him someplace a lot faster than a bike. Sure, that's true…but a car will also burn gas. No problem—this is just another great math opportunity. Use addition and division to calculate miles per gallon and cost per mile…and speed your child into a future full of all sorts of math learning!