This problem encouraged Cao Kha Tien - a high school student in Thua Thien-Hue Province - to invent a chalkboard cleaning machine that minimises chalk dust. This machine is based on the suction of a small fan. Chalk dust is retained in a small container.
Cao Kha Tien's invention shows his creativeness and kindness. The chalkboard cleaning machine won the first prize in the Adolescents Creativity Competition. Tien has made the machine more compact and improved its suction force. He will send the machine to the national competition in the coming time.
