Son not being careful in class

Not long ago my son not being careful in class, his hand injured by the sharp corner of the white board. He says he cried in class, teacher brings him to office to put medication on his hand. 

This happened in 21 May, 2014 as I have informed dear about this. 

This gives him a scar on his hand. 

Another incident happened at tuition center, a standard three boy which is a year older than uses finger's nail to scratch his nose. It leaves leave cut to his nose. This happened in August. 

These were the days he told me he cried because it hurt so much.