Is there much of a difference between 99.9% or 99.999%?

Use our present need for cleanliness to engage your students.

Clicking on this image will show it larger in a new window.

Does it really matter whether you kill 99.9% of the bacteria or 99.999% of the germs?

In this 3-act activity we've asked students to consider whether these claims about these two wipes' efficacy really make a difference.  We've supplied students with a list of bacteria counts on various surfaces and asked them to calculate how much of a difference these two different percents make in wiping out germs.

This is an excellent opportunity to deal with repeating decimals.  

Celebrate Saint Patrick’s Day (3 activities)

Finding 4-leaf clovers!

Shamrocks in Ireland are actually be 3-leafed white clover, trifolium repens. If you are lucky, you can sometimes find a four-leafed clover.  How rare is finding a 4-leafed clover?  How hard do you have to look?  What size area of clover must you examine to find one?

The R-naught number of the coronavirus

Click on this image to see it larger in a new window.

There's a number used to quantify how fast a virus will spread, the R-naught number.  As the coronavirus is spreading though out the world, let your students see how the threat of infection is measured and understand the mathematics of judging how a population will be affected.

It’s time to gear up for Pi Day

Why do we have the clock set at this time? Click the image to find out.

8 possible activities!

Celebrate π in your school and in your math class with activities that demonstrate how π was derived; visually show why π makes sense; show a surprising place where π is used; increase students ability to measure and long divide; applauds the talent of people who can memorize large strings of numbers; and lets students just have fun.

PiDay-ClassOpener - Puzzle to ponder with a surprising outcome.

     For members: PiDayClassOpenerSolution.pdf


What is Pi?.pdf - The logic of finding the perimeters of inscribed and circumscribed polygons as the number of sides to the polygons increase.

    For members:  What is Pi-solution.pdf

Which gasoline is the cheapest?

Euros per liter in Crete, Greece

Dollars per gallon in Framingham, MA

When Brian traveled to Crete last summer with his wife and son on an Archaeological dig, buying gasoline for his small rental car got him wondering again.

He was pretty good at understanding the value of Euros by changing prices into dollars but figuring out the cost of gasoline in Euros per liter versus dollars per gallon was confounding him.

  • Should he figure out how many gallons of gas he could get for one Euro?
  • Or how many liters of gasoline he could get for one dollar?
  • Is gas, and therefore, driving more expensive in Greece?
  • Can you figure it out?