This is a special post for all the teachers out there. Although I have seen the high tech boards in some high school classrooms, I know that many of you still use chalk and write on chalk boards due to school district budget constraints. Here are some other uses for chalk - yes, this is white white chalk used on blackboards. or
Repel ants - Keep ants at bay by drawing a line around home entry points. The ants will be repelled by the calcium carbonate in the chalk, which is actually made up of ground-up and compressed shells of marine animals. Scatter powdered chalk around garden plants to repel ants and slugs.
Polish metal and marble - To make metal shine like new, put some chalk dust on a damp cloth and wipe. (You can make chalk dust by using a mortar to pulverize pieces of chalk.) Buff with a soft cloth for an even shinier finish. Wipe clean marble with a damp soft cloth dipped in powdered chalk. Rinse with clear water and dry thoroughly.
Keep silver from tarnishing - You love serving company with your fine silver, but polishing it before each use is another story. Put one or two pieces of chalk in the drawer with your good silver. It will absorb moisture and slow tarnishing. Put some in your jewelry box to delay tarnishing there too.
Remove grease spots - The chalk will absorb the oils that hold dirt in. Rub chalk on a grease spot on clothing or table linen and let it absorb the oil before you brush it off. If the stain lingers, rub chalk into it again before laundering. To get rid of ring-around-the-collar stains, mark the stains heavily with chalk before laundering. The chalk will absorb the oils that hold dirt in.
Keep tools rust-free - You can eliminate moisture and prevent rust from invading your toolbox by simply putting a few pieces of chalk in the box. Your tools will be rust-free and so will the toolbox.
Source: Extraordinary Uses for Ordinary Things (see Amazon link in the top left)