scale did not move smoothly.what canＩdo?
We can't lift up pet bottle.
Balance scale is great!
l turn the gear exactly.
You might also want to use a timer.
It's hard to balance
the thimio didn't work exactly so, we mend pipe cleaner many times.
i fixed color of tape black to white
Paper cups make almost no noise.
drum bot is funny. it rolls drum slowly .