In this delightful, science-packed picture book, readers will join two groups of young friends as they each plant a tree and then share their excitement through a series of penpal letters. In the UK, the friends plant an acorn and share all the facts about how their oak tree will become a maker of oxygen, a cleaner of the air, a feeder of the soil and a home for thousands of tiny creatures. In Senegal, in the Sahel region of Africa, the friends plant an acacia tree that will become a source of income for their family and part of the Great Green Wall that will stretch across Africa, protecting the Sahel from the Sahara Desert. This uplifting story will give readers plenty of information about trees and includes a Plant Your Own Tree activity.