Tree Measuring: Take the children outside; take a ball of string and scissors with you. Use the string to measure the circumference of 3 or 4 trees nearby. Put each string in a baggie. Label each baggie; refer to the tree from which the measurement was taken. Bring the strings inside and measure each string with a tape measure. Compare the circumferences of the trees by looking at the standard number from the tape measure and compare the lengths of the strings. Discuss why the circumferences vary. You can graph your findings as well.