For example, to prove that the three angles in a triangle always add up to 180 degrees, he had his children cut out different sized and shaped triangles from colored paper at home, as well as use a string to make a triangle as big as an exercise field, and then measure the angles.
例如要證明三角形的內角和，他就讓小朋友們回家用色紙剪出大大小小的三角形，還在戶外拉出一個如操場大的三角形，量其角度。