Charlie demonstrates the Marble Tester 3000

Charlie (in official J-list Gojira shirt) demonstrates the Marble Tester 3000 at the Science Fair. We learned a LOT building this—not only skills, like how to solder and how to drill through acrylic without cracking it, but also principles, like how to tune a device after constructing it. The lighter balls (aluminium in particular) didn't press hard enough on the contact strips to make a good electrical connection, so sometimes they wouldn't light at all and other times they'd only flicker. And sometimes they'd ride up and only make contact with one of the strips. So we put in an additional set of jumper wires as "bumpers" to guide them into the track. Worked a little better... but still not enough.Slowing down the balls' travel helped, so the device ended up having even less slope than shown here.Best of all, though, it was a HUGE hit with the kids and parents, though Kim noticed that dads spent more time reading than moms did. Kids loved rolling the different colors and weights of balls down the tube and watching the light come on, or not. And Lego is the ultimate building material because if it comes apart, you just push it back together again.Next year we want to build a death ray...We celebrated with our traditional trip to Rose's for Dr. Brown's Black Cherry Soda and, in this case, their special chocolate mousse cake for Charlie. Yum.