There is a kind mother whose name is pencil case. She gave birth to four daughters.

One day, she prepared a long ruler to test her daughters' learning about measurement.

The eldest daughter said,' My name is eraser. I'm short and fat.' Say that finish, standing in front of a long ruler, only 2.5 cm high; The second daughter did not show weakness and said,' My name is Triangle, and I look like Triangle.' After that, I was still standing in front of a long ruler, which was 7.5 cm high. The third daughter said,' My name is a ruler, which is flat and long. Look at me. Say that finish, he proudly stood in front of the long ruler, yeah! 15 cm high; The fourth daughter said unconvinced,' My name is mechanical pencil, and I'm long and round. I am the tallest of the four sisters. Then swaggering to the long ruler, ah! 16 cm high. My mother said happily,' You are all my good daughters. ' '

I stood by and thought: I also learned to measure.