But it seems the whole chalk dust-up may be overblown ... Back in March, Mortensen let her 4-year old daughter draw a “door to magic land” on rocks at Belle Isle, a granite-studded ...

Chalk dust is spread in the path of a laser beam. The dust scatters light in the beam path, showing it moves in a straight line. Mount the laser on the lab stand, with the laser pointing to the side ...