Sarah and Max have to tie ropes around the tree trunk and several branches. They know the thickness (= diameter) of the branches and trunk at the various points, but still have to find out how long the rope has to be.[br][br]Max borrows a tree slice from his grandfather. It is a decoration hanging over the fireplace in grandpa's living room.[br]It has a diameter of 26 cm and a circumference of 82 cm.

When looking at the slice, Max and Sarah reckon with your aid, it should be fairly easy to estimate diameter and circumference. [br][br]Take the following material out of the box: