Wednesday, November 19, 2008

Case Study: Time Based Data Practical in Google Earth

I thought today I'd describe my efforts with a recent piece of work I've been working on: Enhancing some excellent data from the NASA visualization lab to be put in a practical for students on an introductory course in Oceanography at Southampton University.

Plankton Bloom around Galapagos Islands from practical. Red indicates high density.

Data Set and Central Challenge: The data I was enhancing was changes in sea surface temperature and also plankton density with time (the two have an important relationship that I won't go into here) during an El Nino event. The central problem of the practical was that dealing with multiple sets of time data is tricky and I planned to have the (400!) students attempt the practical unsupervised so there was no one on hand to help them out if they got stuck.

Approach 1 Issues: My initial approach was to produce a video tutorial to cover the aspects of timeline control they would need and then direct them to manipulate a single Google Earth file. The tutorial here is a low bandwidth version of that video tutorial. However, whilst testing the practical before release on two likely users I discovered they were still struggling with 2 main problems:
  1. Dry Content: The tutorial explained a number of pretty dry concepts (e.g. dragging timeline handles to download images) without getting the students to immediately apply the concepts, as a result they didn't really concentrate on it.
  2. Tricky Controls: Manipulating the layers was still tricky even after watching the video tutorial, it requires you to tick the right boxes, make sure the right layers are selected and also understand how to manipulate the timeline.
Getting the students to grapple with problem [2] is a good thing, learning to manipulate web map systems is a skill that can then be transferred to other applications. However, problem [2] was bigger than expected so it was unfair to ask the students to deal with it IMHO, especially because the practical was unsupervised.

Approach 2: Instead of 1 google earth file I gave the students 3 separate ones to open at different points in the practical with the layers arranged correctly within each file. This meant they didn't have to work out how to manipulate the data as I had set the folder structure up in advance (as discussed last week). I still had to teach them about some aspects of the timeline but I managed to do this using static diagrams within a set of written instructions. These two approaches allowed me to ditch the video tutorial completely, I failed to teach them many skills about layer control but IMHO this was worth the sacrifice.

Lessons I draw:
  • MOST IMPORTANT - Testing: This sort of thing only appears when you do some kind of testing of your content before release. You don't have to kill yourself with this, hallway testing is sufficient.
  • Splitting Content: Splitting the content up into different Google Earth files was a useful strategy in this case. Its a useful strategy elsewhere (#7 of my review points).
  • Keep it Simple Stupid: In the end, the simpler solution is often the best, I'm often pleased with the clever things I've done but in this case when it proved ineffective, I was prepared to ditch it.

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