My kid has this habit of biting his nails. How can I correct this habit of his?

I put plaster on my child ten fingers... the sticky part excluding the white cushion part... I cut into ten mini strips and paste on the fingers... as the sticky part is quite sticky on the nails and hence will not drop off easily... since the colours are very vibrant (use kids plaster) hence easily catch the attention and rem not to bite... it works the teacher said... hee hee