Reflecting Clouds

I was driving my son to school and we were planning DIY project which would use solar panels as energy source. As conversation goes on I explain that solar panel would charge battery during the day and then we can use it to power things during the night. He agrees and then asks “Why can’t we use black panels?”. His logic is straight forward if solar panels work during the day then there must be “black panels” that work during night time… It’s so interesting to follow kids thinking when its roaming free, the reasoning the obstacles, and solutions.

I have lots of fun watching our kids to play “River Crossing” from ThinkFun. For example an interesting observation is that the longer the plank the harder it is to rotate it! They have no problem rotating small planks on the whim, however constatntly forgeting that long ones can be rotated just as easily. May be its psyhological perception that long planks are bigger and heavier, who wants to haul them around. Another observation is long way seeds doubt in their mind even if they are are on the right track. If there are too many moves which take them long way around the game field they begin to doubt themself and look for shorter way.

Here is nice Guilloché pattern generator done in form of a web app. Guilloché is an engraving technique where precise and repetitive pattern or design is mechanically etched into an underlying material (ussually metalic surfaces) with very fine detail. See Wikipedia article for details. These patterns have long history and were used as ornaments by crafters since 17th century.

The generator is pretty neat, now we need to have all that in 3D…

There is interesting way to multiply numbers in second half of multiplcation table (6-10). Which I found in my old notes, not really sure where it came from.

On each open number of fingers that is difference between operand and five (one hand per operand). For example to multiply 6 by 7 you open 1 finger on one hand (6-5=1) and 2 fingers on another (7-5=2), then you multiply number of closed fingers on your hands and add it to sum of open fingers multiplied by 10. In our case:

4 (closed fingers on one hand) x 3 (closed fingers on another hand) + (1 + 2) * 10 = 42 which is result of 6 x 7.

Another example:8*9 translates to:
2*1 + (3+4) * 10 = 72

pretty neat