Teachers, don’t use these in class

I have nothing against large companies providing free didactic materials like videos and images to support education. But the below Sankey diagram samples from the image bank of a large multinational company are a fail!

Teachers should better not use them in class, as their smarter students may identify the fundamental error in them:

Can you spot the error?


  1. Toby says:

    I guess the scaling width for 100J is different in the two diagrams. Hence, the 75J light energy above appears even more impressive compared to the 10J below. Anything else?

  2. phineas says:

    @Toby: the two Sankey diagrams I show together in one post were individual files. So I think it is OK that each of them has its own scale.
    But the main problem is a different one … you might need a ruler to find out.

  3. Toby says:

    I give it a second try: 90J does not equal 100J! Width-wise it does so, though (in lower Sankey)

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