Warning! JavaScript must be enabled for proper operation of the site.

Penny Circle

by Dan Meyer


Act One

  • Dan Meyer

    Dan Meyer

    September 24, 2012

    How many pennies will fill the large circle?

  • 1.

    What's a number you know is too high?

  • 2.

    What's a number you know is too low?

Act Two

  • 3.

    What information would be useful to know here?

  • ImageThe diameter of the large circle
  • 4.

    How can we use smaller circles to figure out how many pennies are in the big circle?

  • FileEmpty Circles
  • FileFull Circles
  • Teacher note
    Depending on your available time and materials, give students the empty circles handout, a ruler, and pennies so they can collect their own data. Or if you're more pressed for time give them the full circles handout so they count.

Act Three


  • Image2000 pennies
  • 5.

    How big is the smallest circle that would enclose 2,000 pennies?

  • 6.

    How many pennies lie along the circumference of the big circle? Do you think that model will be quadratic also? Why or why not?

  • VideoAnswer

show 52 more questions


Join or sign in to leave a comment.