We have a lot of water on Earth, but we also can't actually drink much of it... or use it for farming. That's because most of the water on Earth is saltwater. We humans, like a lot of living things, need freshwater to survive. In this episode of Crash Course Kids, Sabrina talks about the difference between freshwater and saltwater and why freshwater is so important.

Look inside a resistor to see how it works. Increase the battery voltage to make more electrons flow though the resistor. Increase the resistance to block the flow of electrons. Watch the current and resistor temperature change.

Look inside a resistor to see how it works. Increase the battery voltage to make more electrons flow though the resistor. Increase the resistance to block the flow of electrons. Watch the current and resistor temperature change.

This article describes the urban heat island phenomenon and provides an overview of a research project investigating the effect as seen in New York City. Topics include the large proportion of earth's population now living in cities and the exacerbating effect of climate change on heat islands. A discussion of the study in New York describes how researchers used LandSat imagery to correlate the hottest areas of the city with a lack of vegetation (especially trees) in those areas. Suggested mitigation solutions included planting more trees, converting roof surfaces to reflect light, and the use of 'green roofs', specially constructed systems that use living plants as the outermost layer.

Learn about the Cree Calendar and what the different months of the year mean.

Since 2004, the Bertino Forensics Science Institute has become a leading forensics training programs for teachers in the United States attracting participants from over thirty states and as far away as Myanmar, Taipei and Russia. Our program includes our forensic textbook (Forensic Science: Fundamentals and Investigations), additional teaching resources and teacher education opportunities through workshops, conference presentations, seminars and Webinars. These provide educators with hands-on experiences that inspire and educate students in the principles of scientific inquiry, analysis and creative thinking.

Fourth graders are independent explorers, full of ideas and opinions. They have an impressive skill set and are ready to go deeper. With that in mind, we’ve gathered together learning links and fun activities that will help kids build skills in literacy, math, science, and social studies—plus some just for fun! This list of 4th grade websites and activities is something kids can easily do at home with their families.

Fifth graders are on the brink of adolescence. They are curious, capable, and ready to tackle the world. With that in mind, we’ve gathered together learning links and fun activities that will help them build skills in literacy, math, science, and social studies—plus some just for fun! This list of 5th grade websites and activities is something kids can easily do at home with their families.

Second graders are full of curiosity and enthusiasm for learning. Parents can supplement any education with these amazing second grade websites and activities kids can enjoy at home with their families. (They won’t even know they’re learning!) These learning links and fun activities will help kids build skills in literacy, math, science, and social studies—plus we included some that are just for enjoyment.

Third graders are curious, capable and eager to share their ideas. With that in mind, we’ve gathered together learning links and fun activities that will help kids build skills in literacy, math, science, and social studies—plus some just for fun! This list of third grade websites and activities is something kids can easily do at home with their families.

Did you know that all living things change their environments? It's true. Beavers, deer, worms, and humans all change their environments. It just so happens that humans change our environments in big, obvious ways. In this episode, Sabrina chats about how humans have been changing our environments for a long time!

What do beavers, termites, and prairie dogs have in common? They all change their environments! We know that humans change their environments, but humans are animals and all animals change their environments just by living in them.

Hank tells us the story of the complicated chemical dance that allows our skeletal muscles to contract and relax.:Cardiac, Smooth, & Skeletal Muscles,Muscle Anatomy ,Muscle Fibers, Myofibrils, Sarcomeres,Myofilaments

Hank tells us the story of the complicated chemical dance that allows our skeletal muscles to contract and relax.

Series of videos on the Big Bang, Universe and Evolutionary history created by the team at Crash Course

Hank talks about the molecules that make up every living thing - carbohydrates, lipids, and proteins - and how we find them in our environment and in the food that we eat.

Biology Simulations helps students to learn about biology and practice data analysis skills. These simulations allow students to experiment with concepts that may take too much time or too many resources to complete in a traditional science lab setting.

Simulations and virtual labs for biology topics including evolution, ecology, and cellular energetics. All materials are free

We’ve talked about different materials engineers use to build things in the world, but there’s a special category of materials they turn to when building things to go inside our bodies. In this episode we’ll explore the world biomaterials like titanium and their coatings, the special chemistry of polyurethane, and the cross-linked structure of hydrogels. We’ll also look at the importance of safety & research, as well as the enormous future potential of biomaterials.