Blog reader Panalion sent me a photo taken in Amsterdam’s Botanical Garden. It is of a map showing coffee and tea flows from producing countries to mainly Europe and North America. Panalion writes “I thought you might like this Sankey map I found attached to a cable between two palm trees. There were chairs set up to accomodate school classes”.
This map is for didactic purposes and features no absolute figures and no year. In addition to the export flows of coffee and tea shown as arrows the map also has circles of three different sizes representing percentage of world production of coffee, tea and cocoa in the originating country.
Infographers might have better ways of showing this information. But in this case I think it is sufficient to get the message across to the target audience, the school kids.
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?
Mr. Palmer, a UK physics tutor, has many of his physics lectures for General Certificate of Secondary Education (GCSE) online, with notes and illustrations. You can find topics such as “motion”, “heat”, “nuclear radiation”, and even “the origins of the universe”. Very infomative, and well illustrated, even if you are not a high school student.
To attract student’s interest and make them understand efficiency in the “electricity” topic, he asks them to draw a Sankey diagram for their iPod.
The three Sankey diagram examples Mr. Palmer shows in his notes use the simple but effective grid paper approach that I have shown in this post.
I have tried to get to the numbers behind the diagram, but even in the tech specs, in the product environmental report for the iPod and on Apples environment website, they don’t give details on how much of the power is used for screen lighting and sound, and how much is lost as heat. So I guess that Mr. Palmer might have made these up, and that the energy efficiency of 31% for the iPod is just an arbitrary number…
Even though I didn’t find the hard facts, I came across some ideas and fancy gadgets for the iPod, that make its use “greener”, even though they do not increase the energy efficiency of the appliance itself:
- solar chargers for the iPod, such as the one from Solio, also used by President Obama, or this denim jacket with embedded solar panels
- wind power chargers for the iPod, that you can attach to your bicycle or to your arm, such as this one
- for women only: a solar charger bra and next generation breast motion power generators (yes, you read correctly, this ain’t an April fools day joke!)
- the advice to use the socket to charge your iPod (“Charging your iPod from your computer uses around 15 – 20 watts while charging it from the wall uses only 3.8 watts.” from todae energy efficiency guide)
And of course there are several hints, that help to really reduce energy consumption and make your iPod more energy efficient, such as dimming the display and avoiding to do a skip search on titles.
Browsing for more Sankey diagram goodies the other day I was delighted to find the following sketch in a brochure ‘Let’s learn about energy: a practical handbook for teachers’ published by the TACIS technical dissemination project.
The diagram illustrates a list of suggested activities for students, to teach them “why energy is important”:
Get students to draw up Sankey diagram (Figure 3) showing the energy flows through a process or activity. Consider a power station, house or car. The width of the arrows represents the amount of energy. Energy inputs (fuels, electricity) usually flow into the process from the left and useful energy outputs (heating lighting mechanical power, chemical energy) and losses (heat, noise etc.) flow out to the right.
And another language for my collection of Sankey definitions…
The site has a demonstration of how Sankey diagrams may be used to represent transfer of energy, including a PowerPoint and “stories”, for which pupils can create a Sankey diagram by using tokens cut from cardboard.
I think this is a great idea, as it supports the understanding of the energy topic with a haptic and, very importantly, a visual approach.