Some engineering teachers don't allow students to draw with mechanical pencil. What is the reason?

Mechanical pencil is not suitable for students because of its different quality and weight. Most mechanical pencil is made of metal, which has a certain weight. If it is used for a long time, it will affect the work. At the same time, writing for a long time will make your hands ache. If you use mechanical pencil for a long time, your fingers will be more stiff and inflexible. In addition, due to the different quality of mechanical pencil and pencil, many mechanical pencil are of poor quality, which will be easily broken in a short time, and even the refills are particularly easy to break. Repeated replacement will delay the progress and is not conducive to normal classes. Therefore, the teacher does not allow students to draw with mechanical pencil.

Mechanical pencil didn't dare to write hard, which was not conducive to drawing lines. In the end, the effect is hard to see clearly. It's best to write in pencil. Pencils are simple in shape, full of wood, practical, not very effective in wood utilization, and will not cause wood waste, but it is more laborious to sharpen pencils. If you use mechanical pencil, if you don't have a good grasp, the writing refill will break easily. Dare not write hard, it will cause writing instability and affect the beautiful lines written. There is a reason why teachers don't allow students to draw with mechanical pencil. Drawing during exams may even affect their grades. Mechanical pencil has great security risks. If an accident happens in class, the teacher is also responsible.

Pencils are smooth to use and especially suitable for drawing. Mechanical pencil knows that the refill is easy to break. If you have used mechanical pencil, you will know that pencils are more suitable for drawing in the end. Generally, the drawing paper will be thicker. When mechanical pencil comes across these thick papers, his drawing will not be very smooth. If students change refills many times in class, and the last broken refills are scattered on the floor or on the table, I believe teachers will be very unhappy. After a class, teachers will focus on changing refills. Who wants to concentrate on the class?