3 years & up. Encourage your children to discover and explore the outdoors with these Let's Take a Walk and Explore Nature Early STEM Concepts Books. Children will enjoy learning about the different elements of nature such as rocks, leaves, oak trees, maple trees, flowers, and seeds. Complete with beautiful photographs, children can explore and point out familiar elements they may encounter on walks. For extra learning, have a discussion about ecosystems or the animals that thrive from the different elements. Set of 6 paperback books.