This 14-minute video lesson looks at how a sodium potassium pump can maintain a voltage gradient across a cell or neuron's membrane. [Biology playlist: Lesson 42 of 71].
This 13-minute video lesson looks at the science of taxonomy and where humans fit into the tree of life. [Biology playlist: Lesson 62 of 71].
This 19-minute video lesson provides an overview of how the nephrons in the kidney filter blood and reabsorb water and other molecules. [Biology playlist: Lesson 59 of 71].
This 9-minute video lesson looks at tropomyosin and troponin and their role in regulating muscle contraction. How calcium ion concentration dictates whether a muscle is contracting or not. [Biology playlist: Lesson 48 of 71].
This 23-minute video provides an introduction to viruses. [Biology playlist: Lesson 19 of 71].
Overview of biology, the study of life.
Birth of Stars. Created by Sal Khan.
Bit-zee is a project designed to inspire students to explore math and science. It was created from everyday items (a hair dryer, tap light, alarm clock, digital camera, and a universal remote). See the following link for help with the code https://sites.google.com/site/khanacademyprojects/home. Created by Karl Wendt.
Bit-zee goes to school. Created by Karl Wendt.
Black Holes. Created by Sal Khan.
Calculating electron energy for levels n=1 to 3. Drawing a shell model diagram and an energy diagram for hydrogen, and then using the diagrams to calculate the energy required to excite an electron between different energy levels. Created by Jay.
Using classical physics to calculate the energy of electrons in Bohr model. Solving for energy of ground state and more generally for level n. Created by Jay
Using equation for Bohr model radii to draw shell model for n=1 to 3, and calculating the velocity of a ground state electron. Created by Jay
Using classical physics and vectors, plus assumption that angular momentum of electron is quantized, to derive the equation for Bohr model radii. Created by Jay.
One way we can prove that we are calculating the actual touching point.
Jessica introduces the idea of "booleans", values that can either be true or false.
David shows how to use conservation of momentum for a situation where two objects bounce off of each other. Created by David SantoPietro.
Overview of how chromosomes were first proposed as the carriers of Mendel's "heritable factors" (what we now call "genes").
Sal explains how to draw free body diagrams when forces are applied at an angle. How to find horizontal and vertical components of an angled force using trigonometry.
Breaking down photosynthesis into light dependent reactions and Calvin cycle.