PROTRACTOR

Last night, when I reached home, Venus showed me her maths textbook pointing to the picture below said she need for her class today.  

After dinner, she started to look into her assets and couldn't find it. Then the whole family started to look around the house for the little protractor. Everybody looked high and low, up and down still cannot find. So I passed the below to her.

She said cannot. It is different, no lines in the middle, cannot use.


pengz..........................................................................