I recommend they try another method for distance.  Time (10 sec) will remain
constant but the distance traveled will vary with the power of the
batteries.  You'll find the rotation sensors (rotations or degrees) will
give them a much more reliable metric.  You can incorporate math (Diameter
of the wheel x pi = circumference for one rotation) to calculate degrees of
rotation to achieve a given distance.


On 10/8/10 10:05 PM, "Heather Houlden" <[log in to unmask]> wrote:

> It is my first year as well, so we are learning too. However, my kids are
> measuring the distances the robot needs to travel.
> We programmed the robot to travel in a straight line for a set time (I
> think it was 10 sec). Then they measured the distance travelled, and I
> had them compute the seconds per inch travelled.
> 
> Then they just multiply the seconds/inch by the number of inches the
> robot needs to move, so that they can program the number of seconds
> to move. 
> So far it seems to be working OK for them. There may be an easier way
> to do it, but this is what they came up with.
> Hope this helps!
> Heather
> Team Blockbusters
> 
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