P.S.: I'm running another math book giveaway, on my blog this time. If you'd like to enter, the information is here.

Also, there's a little over a week to get in on my Math Rebels Kickstarter. Don't miss out!

Finally, I'm not sure if I've mentioned it, but my Prealgebra & Geometry Games book is now available for preorder at all the regular bookstores (ebook and paperback). Publication date is February 23!

Follow this link to download the Heartstrings pattern. Use colored pencils or markers to connect the dots.

Each quarter of the page is a string-art design consisting of two lines that meet at that corner. The two hollow dots on the right and left sides of the page are used twice (for the top and bottom patterns), as are the dots at top and bottom center.

For each corner pair of lines, connect the farthest-out dot on one of the lines to the closest-in dot of the other. Then continue from one dot to the next, letting the lines criss-cross to create the design shown.

A cardioid is a heart-shaped curve traced by one fixed point on a circle that rolls around the circumference of another circle with the same radius.

This free "Draw a Cardioid" project is string art for middle or high school students. It takes some careful ruler work, lining up the points, but my students were delighted to see the heart appear as if by magic.

You can find more string-art patterns on the Math Cats String Art webpage.

After trying their examples, make up a design of your own. Use a ruler or any straight edge to draw two lines. The lines can meet at a corner, or they can cross, or they can each stand on their own. They don't even have to be straight (the cardioid used a circle). Every combination will make a different design, so experiment to discover what you like best.

Mark dots along your lines. Start with evenly-spaced dots, or experiment with other spacings. Now choose a pattern for connecting the dots. Traditional string art connects crosswise — matching the farthest dot on one line to its opposite, closest-in partner on the other — but different connecting rules create their own cool designs.

Don't you love how the straight lines of string art form an illusion of graceful curves? In calculus, we also use straight lines (the derivative) to help us "see" curves more clearly.

Try drawing a simple curve and finding several tangent lines, the derivatives of the curve at those points. How might you create that curve using string art?

[Activity from chapter 4 of Discovering the Art of Calculus.]