Mr. Andersen talks you through the diffusion demo. After you finish watching this video you should be able to rank the following from smallest to largest: starch, glucose, water, IKI and the pores in the dialysis tubing.

In this video Paul Andersen explains how biodiversity measures the variety of genes, species, and ecosystems on the planet. Biodiversity provides resources and ecosystem services for humans on the planet. He also explains how...

In the world of ecology, the only constant is change - but change can be good. Today Hank explains ecological succession and how ecological communities change over time to become beautiful, biodiverse mosaics.

What do Euclid, 12-year-old Einstein, and American President James Garfield have in common? They all came up with elegant proofs for the famous Pythagorean theorem, one of the most fundamental rules of geometry and the basis for...

In this episode of Crash Course Physics, Megneto helps Shini explain what induction is, how it works, and why magnetism is so seemingly complicated.

Paul Andersen describes the major mutations found in the living world. He starts with an analogy comparing the information in DNA with the information in a recipe. Changes in the DNA can result in changes to the protein, like changes in...

What does an atom look like? Throughout history scientists and philosophers have attempted to answer this question. As a result, they've come up with some useful models for understanding the building blocks of our universe.

How to Build a Better City

On the 4th of July, Americans like to celebrate the things that make the United States unique, and a lot of those things have to do with our geography. That remarkable geography is also responsible for some pretty unique weather, and...

In this video Paul Andersen explains how the mechanical energy added or removed from a system results from work. For work to occur a force must act parallel to the displacement of the system. Since work and energy are equivalent the...

Paul Andersen explains how enzymes are used to break down substrates. The correct shape of the active site allows a key/lock fit between the enzyme and the substrate. The enzyme catalase is used to break down hydrogen peroxide. The...

In this video Paul Andersen explains how various techniques have been used for years to collect seafood. Commercial fishing has led to overfishing in certain areas and species due to the tragedy of the commons. An explanation of...

Hank tells us about the enormous concentrations of plastic debris floating around in the Pacific Ocean, why they're there and why they're a problem.

Today Hank talks about your central nervous system. In this episode we'll explore how your brain develops and how important location is for each of your brain's many functions. Table of Contents Central Nervous System, Location and Brain...

Paul Andersen explains how organs work together to form organ systems and how organ systems work together to form organisms. The kidney and bladder work together to filter blood in the excretory system. The circulatory and respiratory...

Hank reviews the latest in science news, including the discovery of Element 115, the biggest volcano on Earth, and new insights into what it might mean to have small testicles.

GPS devices aren't just for keeping you from driving into a lake. They're also helping lots of scientists in unexpected ways.

Have you ever moved? Some animals move too! And if an animal moves from one place to another for weather or food, it's called migration!

What happened when a gambler asked for help from a mathematician? The formal study of Probability.

Straddling Virginia and North Carolina is an area that was once described as the "most repulsive of American possessions." By 1728, it was known as the Great Dismal Swamp. But while many deemed it uninhabitable, recent findings suggest...

In this video Paul Andersen answers the very simple question: What is cancer? He explains how damage to the DNA can create uncontrolled cell growth. He explains how malignant tumors can spread the disease throughout the body and gives...

You might guess that big city subways would be filled with all sorts of nasty pathogens just waiting to infect the nearest unsuspecting human, but science doesn’t back this up at all.

How successful are we compared to other species? It turns out that biomass, or what things weigh, can be more important than how many of something there are. Find out how our numbers stack up against everything from bugs to bacteria, and...

Did you know you can read the story of a tree's life? By looking at a tree's rings, you can figure out way more than just how old it is! Jessi and Squeaks are here to show you what to look for next time you're on a hike and find a tree...