In the Jack and Jillian book series, Jack and Jillian write about learning, and creating, new things. When Jack and Jillian go camping, they write about camping in a national park, hiking, the animals, how they live, and camp, in a national park. The Jack and Jillian Book Series are aimed at encouraging, challenging young minds, and motivating them to remain active, both physically and mentally. Recommended for children 4 to 8.