"Correct!" responded Charlie. And they continued on their way.
"Charlie," said Henry after they'd walked some distance in silence, "can we find out how old a tree is without having to chop it down?"
Charlie paused. Obviously, Henry had been thinking a lot about this - no wonder he had been so quiet!
"There are some ways we can estimate how old a living tree is," Charlie replied, "but it will only be a general idea - it's not as precise as counting growth rings."
"Can we try anyway?" asked Henry, full of enthusiasm for working out the age of a tree without damaging it.
"OK. Let's try a very easy way first. We need to measure right round the trunk of the tree," Charlie replied. "I wish we'd brought some string with us to circle the tree trunk, but we can manage without. And then we will have to do some workings-out when we get home."