Sorry, parents. Your kids are hooked on pentominoes.

What are these? Oh…THEY ARE FUN! A pentomino is a 5 square inch geometric figure that comes in a set of 12. They’re used by mathematicians (and teachers) to teach things like perimeter, area, spatial thinking, problem solving, flips, slides, rotations, mirrors, and other geometric concepts.

Also, they’re not fattening, cause zero calories, and are quite entertaining. 🙂

I have ordered 18 sets of pentominoes from Amazon. We got lucky and found an extra set in the package, so we have 19 sets. I’ve offered to sell these to students. We did the math today in class, dividing the total price $48.57 by 19 sets-first using a bar model to estimate-and then using a calculator to get an exact cost of $2.556 per set. Rounding the hundredths place…it’s $2.56 a set. I offered to sell them at $2.50 set to avoid the $0.06 headache rather than round the price up to $3.00 per set. Also we agreed as a class a teacher profiting off pentomino sales didn’t seem okay. A $0.06 loss per set isn’t hard to handle. 🙂

Please send students in with exact change: $2.50 per set. 🙂

If more than 19 students want to buy pentominoes, I’ll gladly order more. IF…if…your child would like to purchase a 3-D set of pentominoes, they are available online from Amazon for $12.97. Click **HERE** to see the 3-D set. I have one of these in class, and I can vouch that they are REALLY fun to work with. I’ll let you order the 3-D versions, okay?

Want to see pentominoes in action? Check out the animation below!