### Educational aims and content

From the same people as the domestic gas meter at the College of North-West London comes a ruler. Like the gasmeter, the ruler is aimed at training people for a real life task. In fact it's pretty useless in more ways than one for measuring things in Second Life because it's at a 16:1 scale and so at its longest it's about 162m long! Not exactly easily wielded even if you couldn't do the sums from the measurements of the prims.

You might recognise the styling of the ruler, which is deliberate: it is designed to look reasonably similar to the rulers the students will use when they are working in real life. It's not an exact copy, but it is reasonably close. Similarly there is only a metric scale - this one copied rather more exactly from the rulers the students will be using - because the students don't need to know how to read an Imperial scale any longer: at least there is one place we're moving to metric fully!

The students take 10 readings and then get their feedback, which is also emailed out to them, which lets them paste it into their work-book as part of their portfolio.

### Technical notes

The main technical note here is the making of the scale. Obviously at 160m it's more than one prim, but juggling the technical limits of Second Life uploads and the building of the ruler was fun. The arrangement of marks and spaces tests the limits of the resolution because the 1024px maximum texture dimension when you've got 1,000mm to a 10m ruler (the maximum on the ruler) and you need the marks to be about 1/4 of the width of the spaces makes for fun. In fact there are 40 textures, each for 250mm that started life as 1000px long and then got resized in Photoshop to be 1024 X 32 px for uploading. Once that process had been started and was working it became a matter of rather boring routine to get all 40 textures sorted out.

Apart from that it took a little while to get the rotation and offsets worked out, but that was really a matter of sitting down with a fresh mind and checking the maths rather than anything too taxing. Starting the process at the end of the day was a mistake, but a quickly rectified one when I looked at it with a fresh mind.

The other challenge is finding space for it! Although 162m will fit into a sim, it is a large proportion of the length of a sim. Fitting it into a prebuilt sim proved more awkward than expected, although it is up and running quite happily now.

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