Tara Haelle

A crack of lightning. The blue glow of a phone screen. A blinking firefly. The blazing sun. A camera's rapid flash. No matter the source, light travels in waves, and it does so at a speed faster than anything else in the universe. But what is light, anyway, and how do we study it?

Squeak! Grrr! CRACK! Shhh! Our world is filled with sounds big and small, pleasant and annoying. But how is all that sound created and what can it do? In this book, readers in grades 4-9 will learn how sound travels and the many roles it plays in our world. Sound helps us communicate, but it can do so much more. You might be amazed at how powerful sound waves can be when they let us see into the human body, set off a massive avalanche, or discover...

The Earth buries its past. Living things that die and then slowly become part of the Earth are called fossils. This is where the skills of a paleontologist come into play. Their job is to find fossils and study them in order to make sense of what was going on here on Earth for billions of years before there were ever human beings. Learn all about the fossil record, the amazing discoveries and where they were found, and what it takes to become one...

When you flip a light switch, it turns on the light. But how? Where does that energy come from? How does it get to the light bulb? Learn about all kinds of energy that power our world and how we can make sure we never run out!

Vaccines are biological substances that cause the human immune system to build up its defenses against specific diseases. Public health officials recommend a series of vaccines for all children, as well as some vaccines for teenagers and adults. But not everyone gets the vaccines they need. Many poor nations don't have the resources to deliver vaccines to every community. Some parents refuse to have their children vaccinated because they don't believe...