We are still in the chalk impression cylinder, small diameter, only a finger-long impression. It is indeed the case, which is the most common form of chalk, and we generally call such marked chalk chalk mark on the blackboard the teacher only needs to use that different colored pens on the line, do not need to have other features, As long as the color can come out on top of distinction. Chalk mark is now more secure, and not so much dust, the largest market, but also a major propaganda feature is chalk dust pollution.

But now on the market there is a special kind of chalk, most, if the function is more powerful, can continue as normal chalk, most notably with medicinal functions, it is that people now want to know a particular chalk thorough, medicine chalk, the most common is that you can kill cockroaches and so some pests. This is actually a good invention. In real life, very practical. For example, children especially liked to doodle on the ground, it is inevitable there will be some pests, especially not clean, the child is not special attention, adults sometimes not so time to time custody. This medicine chalk is especially loved by the moms. So there are a lot of mothers will be for children to buy some chalk puzzle with special functions, so you can make the parents more at ease.