| # | Book Title | Author | |
|---|---|---|---|
| 1 | Earthlets, As Explained by Professor Xargle | Willis, Jeanne | |
| 2 | Earth Hounds, As Explained by Professor Xargle | Willis, Jeanne | |
| 3 | Earth Tigerlets, As Explained by Professor Xargle | Willis, Jeanne | |
| 4 | Earth Mobiles, As Explained by Professor Xargle | Willis, Jeanne | |
| 5 | Earth Weather, As Explained by Professor Xargle | Willis, Jeanne | |
| 6 | Relativity, As Explained by Professor Xargle | Willis, Jeanne |