Ingredients added to trace chemicals, increased the proportion of chalk to write on the blackboard, dust flying phenomenon, sanitation and clean, avoiding the chalk foam offal derived by breathing into occupational diseases. Addition of a small amount of smoothing agents and sticky caking agent, chalk and left the clothes, the teacher a lesson to complete a finger no white marks, no hand-washing.

Adding a small amount of moisture agent, long storage is not bad. Ordinary chalk prolonged storage extremely easy to absorb moisture, hardness decreased, writing easily broken.

Blackboard surface smoothness due to the different requirements of the hardness of chalk are not the same. I have a new generation of clean chalk can be arbitrarily changed its hardness, used does not appear to play a variety of board

Slip or easily broken phenomenon, and writing fluency, effort and feel good.

We can also use chalk in my heart, when we encounter happy or sad things, we can use chalk to write out in your own small blackboard, which is a kind of emotional expression. Especially when we feel very bad, we can use this approach when the hearts of unhappy vent out