Complete the Quadrilateral

(Don Steward, 2013)

Try finding the largest and smallest rhombus, rectangle, trapezoids etc. so their vertices  include a special point and the other vertices lie on the lattice points of a grid. The first half of the video is quite easy, but the latter part is really fun and interesting. These puzzles were inspired by Don Steward’s brilliant blog.

Below – students struggle through a tougher variant. Download it here.

Nothing must be advanced in a positive manner. The mind of the pupil is to be the principal operator; it must instruct, convince, and confute itself; and when it arrives at some important truth or result, it must be through its own powers. It ought not even to perceive that it has been guided thither.

F. J. Grund

Introductory Discourse and Lectures, Boston, 1830

Baobab Education had a clever theme for these type of puzzles – rock climbing walls… When I redo this puzzle I will use their theme. These themes do not make the problem “real world” – no climber looks at a rock wall and sees trapezoids 😉 However themes add interest for those students who need a little bit more to get engaged. Just because the connections are silly does not mean that they are pedagogically wrong.

Standards for Mathematical Practice

MathPickle puzzle and game designs engage a wide spectrum of student abilities while targeting the following Standards for Mathematical Practice:

MP1 Toughen up!

This is problem solving where our students develop grit and resiliency in the face of nasty, thorny problems. It is the most sought after skill for our students.

MP3 Work together!

This is collaborative problem solving in which students discuss their strategies to solve a problem and identify missteps in a failed solution. MathPickle recommends pairing up students for all its puzzles.

MP6 Be precise!

This is where our students learn to communicate using precise terminology. MathPickle encourages students not only to use the precise terms of others, but to invent and rigorously define their own terms.

MP7 Be observant!

One of the things that the human brain does very well is identify pattern. We sometimes do this too well and identify patterns that don't really exist.


Please use MathPickle in your classrooms. If you have improvements to make, please contact us. We'll give you credit 😉

Gordon Hamilton

(MMath, PhD)


Lora Saarnio