I’ve been meaning to share this project idea with Josh Burker, author of The Invent to Learn: Guide to Fun and the Invent to Learn: Guide to More Fun books, for more than a year.

While on one of the fabulous London Walks tours (I’ve done dozens of them) of Chelsea in London last year, I learned that before houses had street numbers assigned to them, people shared cards with a rendering of their home’s fanlight depicted on it. This practice dates back to 1720.

The function of the fanlight is to light a home’s entry way, but many of London’s upscale townhouses feature a semicircle shaped fanlight in which a geometric pattern exists. Each pattern needs to be different, at least in a particular neighborhood, in order to depict the occupants of the home for deliveries and visitors. Below are some of the photos of fanlights I took while walking around Chelsea.

Here’s the project idea…

  • Use your favorite dialect of Logo (Turtle Art, SNAP!, Scratch, etc…) to design a unique fan light. Teachers may support the activity by providing the code for drawing a uniform semicircle in which each student’s fanlight pattern must fit.


This is a good project for employing the concept of state transparency; in programming as in life, it is a good idea to return to where you started. Returning the turtle to its initial starting position and orientation allows you to repeat the pattern elsewhere on the screen and perform various transformations on it.

Try these challenges

  • Use Logo/MicroWorlds/SNAP!/Scratch to program the turtle to draw a row of townhomes with different fan lights in each window.
  • Change the scale of your entire neighborhood.
  • Change the scale of your fanlight window without altering its shape.
  • Allow the user to specify the scale of the fanlight and draw it to that scale.
  • Create a more abstract illustration using your fanlight in different ways.

That’s it!

Happy programming
































Gary S. Stager, Ph.D.is an award-winning teacher educator, speaker, consultant and author who is an expert at helping educators prepare students for an uncertain future by super charging learner-centered traditions with modern materials and technology. He is considered one of the world’s leading authorities on learning-by-doing, robotics, computer programming and the maker movement in classrooms. Dr. Gary Stager is co-author of Invent To Learn — Making, Tinkering, and Engineering in the Classroom and the founder of the Constructing Modern Knowledge summer institute. He led professional development in the world’s first 1:1 laptop schools and designed one of the first online graduate school programs. Learn more about Gary here.

Two-Day Seminars with Will Richardson in October 2019 in DC, NJ, & Boston – Register today!

An old friend of mine, Dr. Barry Newell, is an astrophysicist who was was the Administrator (in the NASA sense) of Mount Stromlo and Siding Spring Observatories of the Australian National University. He now works on the dynamics of social-ecological systems. In his spare time (back in 1988), he wrote two classic books on Logo programming and mathematics, Turtle Confusion and the accompanying book for educators, Turtles Speak Mathematics. Turtle Confusion features 40 challenging turtle geometry puzzles in a mystery format and Turtles Speak Mathematics helps educators understand the mathematics their students are learning.

I was reminded of the books when Sugar Labs, the folks behind the operating system for the One Laptop Per Child XO laptop, featured the challenges as an activity to accompany TurtleArt software on the XO.

Screenshot of the XO Turtle Confusion Activity

The books’ author, Dr. Barry Newell, gave me permission to share digital copies of the book for personal, educational and non-commercial use. Click here to go to the download page.

These books are best used with versions of Logo such as MicroWorlds EX or Berkeley Logo. Some of the puzzles are very difficult or impossible to solve in Scratch, but it’s worth trying if that is all you have. SNAP! is another potential option. TurtleArt is another possibility. Although, mathematical programming is often easiest and best achieved through the use of textual language (IMHO). A bit of dialect translation might be necessary. For example, CS is often CG (in MicroWorlds EX).