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This is an example of a writing robot Handwriting is quite a difficult task for robots, but children find the result interesting.
Out of sync. Because of the effects of gravity, a clock high on a wall should run ever so slightly faster than a watch just below it.
If you want to make really sharp stone spearheads, do like Stone Age cave dwellers did and cook them first. Palaeoanthropologists have discovered that this two-step trick was invented 50,000 years earlier than they previously thought.