L Triominoes

I have been working on creating some interactive content for NRICH over the last few days and it has thrown up some really interesting thoughts.

For each interactive I have been considering the following questions:

  • Who is the user? Is it the teacher who might use it for demonstration purposes or is it a student as part of their learning experience?
  • What is the purpose? Is it to demonstrate a principle? Is it to encourage inquiry? Is it a hook? Is it scaffolding for a hard to access problem?
  • Does it add to the experience? Does it self check? Does it need to?
  • If it is a resource to be used in the classroom, does it reduce prep time e.g. printing and laminating and cutting? Should there be printable resources along side the interactivity for flexibility?

Here is an interactive I created for the NRICH problem, L Triominoes. Let me know what you think!

Which enlargements can you tile with the small L shaped tiles?

I also considered accessibility needs, including our colour blind users. I have used different tones as well as outlining the tiles with black lines. Any feedback on this or other issues would be greatly received! 


  1. I have protanomaly, and I can only easily distinguish three colours - the first and last ones at the bottom of your first image look the same to me. Does the colouring matter? The black outlines definitely help.

    1. I think this might be a GeoGebra bug - if you try to drag the border of a shape, it doesn't move.

    2. Thank you for your comments! So great to have first hand feedback.

      In this case the colours themselves aren't important, though I wanted to draw subtle attention to the different rotations of the original tile.

      Other activities where the colour is important I have made sure to label the shapes for example this one: https://www.geogebra.org/m/gqbKSE6R. Would you have a preference for colour names or numbers, like a sudoku? I put on the names as I thought it would allow for easier discussion in a group situation.

      And yes, I think its a geogebra thing, the lines are defined by the shape and I had to 'fix' them to the shape so that you couldn't distort the shapes! But then I needed them to be visible.

    3. I would prefer shading to labels, or in addition to them. Even with the labels, once I'd completed that 5x5 grid it looked a lot like I had repeat blocks next to each other.


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