One of my biology groups is doing a presentation on the immune system in the next few days. They decided that they needed to wander around the school asking any teacher they could find for interesting games they could use for a presentation. Mr. Schmitt, our new math teacher, recommended the neat video above of a white blood cell hunting down a bacterium. It’s pretty dramatic.
Category: video
Supercell
Impressive footage of a storm near Booker Texas, by Mike Olbinski.
Sulfur Hexafluoride Density Demonstration
Sulfur hexafluoride is transparent, so if you fill a fish tank with it you can’t really see that that tank’s filled with anything other than air. However, since sulfur hexafluoride is denser than air, you can float a light boat on the invisible gas for a cool demonstration of density.
Note: Air is about 80% nitrogen gas, which has the formula N2, and a molecular mass of 28 atomic mass units: the molecular mass is the sum of the atomic masses of all the atoms in a molecule. Sulfur hexaflouride has the formula SF6 and a molecular mass of 146 amu, making it about 5 times denser than air.
Alloys are (not Always) Stronger
Steel is an alloy of iron and other elements in small amounts. The exact proportions of the small amounts of other elements can make the alloy stronger, more flexible, and/or more resistant to rusting among other things. Similar alloying is used to make aluminum stronger. You’ll often hear the saying, “Alloys are Stronger” (often used as an argument for more diversity). There is a lot of fascinating research and discoveries happening in the fields of metallurgical arts and sciences at the moment. However, YouTube user NurdRage demonstrates with some gallium and an aluminum can, alloys are not always stronger.
The Physics of Falling Cats
Smarter Every Day uses a high-speed camera to explain the rotational physics how cats manage to spin in the air and land on their feet.
Biology Videos
Sumanas, Inc. has an excellent collection of biology-related videos, including good coverage of mitosis and meiosis.
Khan Academy: The Slope-Intercept Form of a Line
I’ve previously posted an animated illustration of the slope-intercept form, and you can use the straight lines (linear equations) app to check if you’re drawing straight lines correctly.
On Evolution
Carl Segan’s Cosmos series contains a wonderful overview of the history of life.
The one possible criticism of the video is that evolution could be misconstrued as a gradual, linear process (although Segan is pretty clear that this is not the case). BouncingDodecahedrons has an interesting image showing the splitting and coiling of the process.
I prefer to illustrate evolution using the tree of life.
