Earth is a system that exists in dynamic equilibrium. The Earth of today does not look the same as it did millions of years ago. Even the Earth thousands of years ago has distinct differences from the Earth we know today. The Earth’s Changing Surface Interactive E-book* explores how Earth’s ever-changing surface is due to continuous natural processes such as tectonic activity, earthquakes, volcanic activities, weathering and erosion, and sedimentation and the reformation of rock.

The Earth, Sun, and Moon Interactive E-book* uses diagrams, illustrative visual aids, and multimedia to help teachers, students, and other readers understand the interplay between Earth, Sun and Moon, and the characteristics that make Earth unique. It focuses on topics related to the heating of Earth's surface by the Sun, the phases of the Moon, and the apparent changes in the position of objects in the night sky.

The Coral Reef Ecosystems Interactive E-book* explores the structure and inhabitants of a living reef. From the anatomy and reproduction of corals, to their interdependence on other inhabitants of the reef, to the impact of disasters on a reef ecosystem, this Enhanced E-book discusses what a coral reef ecosystem needs to survive and thrive and why coral reef ecosystems are important to our ocean.

The Chemical Reactions Interactive E-book* describes the abundance of chemical reactions in our environment and the variety of reactions involved in biological, chemical, and physical phenomena and how it relates to the electron configurations of and bonding between atoms. This e-book provides an in-depth view of chemical reactions in our everyday world and explains what causes them to occur.

All organisms—from single-celled bacteria to multicellular animals—need to obtain and use energy. The Cells and Chemical Reactions Interactive E-book* takes a closer look at the process of metabolism in cells, including photosynthesis in plant cells and cellular respiration in plant and animal cells. Additionally, this e-book looks at how the rates of these reactions can be affected by temperature, pH, hydration levels, and enzymes.

Cells carry on the many functions needed to sustain life, including cell growth and development. The genetic information encoded in DNA molecules provides instructions for assembling protein molecules, which are both necessary for producing more cells and performing other cellular functions. The Cell Division and Differentiation Interactive E-book* explores these cellular processes for growth and development, including the selective expression of specific genes, which allow for the differentiation and specialization of cells.

The Cell Structure and Function Interactive E-book* explores how cells, the basic building blocks of all organisms, function as systems of organelles and associated structures in a dynamic equilibrium between their internal and external environments. The focus is on topics related to the structure of various types of cells, the molecular workings inside the cell, and the role of proteins as the main structural and functional molecules.

By asking questions, conducting investigations, and interpreting results, scientists now have a better understanding of what makes up the smallest unit of matter that has properties of an element. The Atomic Structure Interactive E-book* uses investigative evidence to examine the structure of atoms and the parts that make up atoms. Additionally, this e-book looks at the forces that hold an atom and an atom’s nucleus together, isotopes, radioactivity, nuclear fusion and fission, and the energy contained in atoms.

The Solar System Interactive E-book* explores what we know about our solar system’s planets, moons, and other celestial bodies. This e-book focuses on asteroids, comets, meteorites, and each of the eight planets in our solar system, including their moons and their rings. Solar system formation theories and technological advances used to study our solar system are also discussed.

The Universe Interactive E-book* explores how the organization of stars and galaxies comprise a universe and how research scientists use specialized instruments to collect data about stars and galaxies. This Enhanced E-book takes a closer look at our star, the Sun, and then uses this information to study the properties and characteristics of different types of stars. Following this exploration, the life cycle of stars, parallax, galaxies, and the organization of the universe are introduced.