Many Let's Read and Find Out titles have either been reillustrated (sometimes more than once) or reissued under different titles. Some of these titles may be duplicates because of the renaming.
Since the 1990s, the series has been divided into two levels. Stage 1 books "explain simple and easily observable science concepts for preschool- and kindergarten-age children." Subjects covered in Stage 1 titles include the human body, plants, animals and "the world around us."
Stage 2 books "explore more challenging concepts for children in the primary grades and include hands-on activities that children can do themselves." Subjects covered in the Stage 2 titles including the human body, plants, animals, dinosaurs, space, weather and the seasons, our earth and "the world around us."
The March of the Lemmings | James R. Newton | Charles Robinson | 1976 | Discusses the physical characteristics and habits of those rodents of the far north whose periodic massive marches to the sea continue to baffle scientists looking for a reason. |
The Moon Seems to Change | Franklyn M. Branley | Helen Borten | 1965 | Outer space | Stage 2 |
The Planets in Our Solar System | Franklyn M. Branley | Don Madden, Kevin O'Malley | 1981 | Outer space | Stage 2 |
The Skeleton Inside You | Philip Balestrino | True Kelley | 1971 1989 | | Human body | Stage 2 |
The Sky Is Full of Stars | Franklyn Branley | Felecia Bond | 1983 | Outer space | Stage 2 |
The Sun: Our Nearest Star | Franklyn Branley | Helen Borten Don Madden, Edward Miller | 1961 1988 | | Outer space | Stage 2 |
The Sunlit Sea | Augusta Goldin | Paul Galdone | 1968 |
The Wonder of Stones | Roma Gans | Joan Berg | 1963 |
Tornado Alert | Franklyn M. Branley | Giulio Maestro | 1988 | Weather and the seasons | Stage 2 |
Turtle Talk: A Beginner's Book of LOGO | Seymour Simon | Barbara & Ed Emberley | 1986 |
Twist, Wiggle and Squirm: A Book About Earthworms | Laurence P. Pringle | Peter Parnall | 1973 |
Upstairs and Downstairs | Ryerson Johnson | Lisl Weil | 1962 |
Use Your Brain | Paul Showers | Rosalind Fry | 1971 |
Volcanoes | Franklyn M. Branley | Marc Simont | 1985 | Earth science | Stage 2 |
Watch Honeybees with Me | Judy Hawes | Helen Stone | 1964 |
Water for Dinosaurs and You | Roma Gans | Richard Gulfari | 1972 |
Water Plants | Laurence P. Pringle | Kazue Mizumura | 1975 |
Weight and Weightlessness | Franklyn M. Branley | Graham Booth | 1972 |
What Color Is Camouflage? | Carolyn Otto | Megan Lloyd | 1996 |
What Happened to the Dinosaurs? | Franklyn M. Branley | 2000 | Dinosaurs | Stage 2 |
What Happens to a Hamburger? | Paul Showers | Anne Rockwell | 1970 | Human body | Stage 2 |
What Happens to Our Trash? | D.J. Ward | Paul Meisel | 2012 |
What I Like About Toads | Judy Hawes | Ruth McCrea | 1969 |
What Is the World Made of? All About Solids, Liquids and Gases | Kathleen Weidner Zoehfeld | Paul Meisel | 1998 | Stage 2 |
What Lives In a Shell? | Kathleen Weidner Zoehfeld | Helen Davie | 1994 | Stage 1 |
What Makes a Magnet? | Franklyn M. Branley | True Kelley | 1996 | Stage 2 |
What Makes a Shadow? | Clyde Bulla | Adrienne Adams | 1962 | The world around us | Stage 1 |
What Makes Day and Night? | Franklyn Branley | Helen Borten Arthur Dorres | 1961 1986 | | Outer space | Stage 2 |
What the Moon Is Like | Franklyn M. Branley | True Kelley | 1963, 1986 | Imagines sights and experiences on a moon visit. | Outer space | Stage 2 |
What Will the Weather Be? | Lynda DeWitt | Carolyn Croll | 1991 2002 | | Weather and the seasons | Stage 2 |
What's Alive? | Kathleen Weidner Zoehfeld | Dadine Bernard Wescott | 1995 | Stage 1 |
What's It Like To Be a Fish? | Wendy Pfeffer | Holly Keller | 2015 | Stage 1 |
What's So Bad About Gasoline? Fossil Fuels and What They Do | Anne Rockwell | Paul Meisel | 2009 | Stage 2 |
When Birds Change Their Feathers | Roma Gans | Felicia Bond | 1986 |
Where Are the Night Animals? | Mary Ann Fraser | 1998 | Stage 1 |
Where Did Dinosaurs Come from? | Kathleen Weidner Zoehfeld | Lucia Washburn | 2010 | Stage 2 |
Where Do Chicks Come From? | Amy E. Sklansky | Pam Paparone | 2005 | Stage 1 |
Where Do Polar Bears Live? | Sarah L. Thomson | Jason Chin | 2009 | Stage 2 |
Where Does Your Garden Grow? | Augusta Goldin | Helen Borten | 1967 |
Where Does the Garbage Go? | Paul Showers | Loretta Lustig | 1974 | Earth science | Stage 2 |
Where the Brook Begins | Margaret Farrington Bartlett | Aldren Watson | 1961 |
Who Eats What? Food Chains and Food Webs | Patricia Lauber | Holly Keller | 1995 2000 | Stage 2 |
Who Lives In an Alligator Hole? | Anne Rockwell | Lizzy Rockwell | 2006 | Stage 2 |
Why Are the Icecaps Melting? The Dangers of Global Warming | Anne Rockwell | Paul Meisel | 2006 | Stage 2 |
Why Do Leaves Change Color? | Betsy Maestro | Loretta Krupinski | 1994 | stage 2 |
Why Frogs Are Wet | Judy Hawes | Don Madden | 1968 2000 | Stage 2 |
Why I Sneeze, Shiver, Hiccup and Yawn | Melvin Berger | Paul Meisel | 1983, 2000 | An introduction to the reflex acts that explain why we sneeze, shiver, hiccup and yawn. |
Wild and Woolly Mammoths | Aliki | 1998 | An easy-to-read account of the woolly mammoth, a giant land mammal which has been extinct for over 11,000 years. | Dinosaurs | Stage 2 |
Wiggling Worms at Work | Wendy Pfeffer | Steve Jenkins | 2003 |
You Can't Make a Move Without Your Muscles | Paul Showers | Harriett Barton | 1982 |
You're Aboard Spaceship Earth | Patricia Lauber | Holly Keller | 1996 |
Your Skin and Mine | Paul Showers | Kathleen Kuchera | 1965 1991 | | Human body | Stage 2 |
Zipping, Zooming, Zapping Bats | Ann Earle | Henry Cole | 1995 | Stage 2 |