Have you ever seen cat pheromones, sometimes branded as Feliway, that promise to address problem behaviors like cat scratching, fighting, and stress? These products are based on real science. But do they work?

At TED U, Gever Tulley, founder of the Tinkering School, spells out 5 dangerous things you should let your kids do -- and why a little danger is good for both kids and grownups.

SciShow tackles one of the cutest questions ever: Why cats knead. You might have heard the theory, but do you know what adult cats would hold on to kitten-like behavior? The answers await!

Can't remember where your soup spoon ought to go? What about your salad fork? Knowing how to set a traditional table can seem like antiquated etiquette -- but it can come in handy! Anna Post, great-great-granddaughter of etiquette expert...

Howcast - Learn how to buy a tactical knife in this Howcast video with expert Dan Delavan.

Howcast - Learn about tactical knives in this Howcast video with expert Dan Delavan.

Howcast - Learn about paring knives in this Howcast video with expert Dan Delavan.

Howcast - Learn how to sharpen and clean your knives in this Howcast video with expert Dan Delavan.

Howcast - Learn how to buy a pocket knife in this Howcast video with expert Dan Delavan.

Howcast - Learn about Santoku knives in this Howcast video with expert Dan Delavan.

Howcast - Learn about chef knives in this Howcast video with expert Dan Delavan.

Howcast - Learn about boning knives in this Howcast video with expert Dan Delavan.

Howcast - Learn about custom handmade knives in this Howcast video with expert Dan Delavan.

Howcast - Learn how to buy a Swiss Army knife in this Howcast video with expert Dan Delavan.

Howcast - Learn what is the best knife for self-defense in this Howcast video with expert Dan Delavan.

Howcast - Learn about survival knives in this Howcast video with expert Dan Delavan.

Howcast - Learn some survival knife buying tips in this Howcast video with expert Dan Delavan.

Howcast - Learn how to buy a bowie knife in this Howcast video with expert Dan Delavan.

Howcast - Learn about butterfly knives in this Howcast video with expert Dan Delavan.

Howcast - Learn about buck knives in this Howcast video with expert Dan Delavan.

Howcast - Learn how to buy a buck knife in this Howcast video with expert Dan Delavan.

Howcast - Learn how to paint with acrylic paint using a palette knife from painter Linda Rhea in this Howcast video.

Howcast - Learn about the best knife for camping or backpacking in this Howcast video with expert Dan Delavan.

Howcast - A brilliant painter needs just the right brush, a great mechanic needs just the right tool, and a true chef needs just the right knife. Choose wisely and half your work is done.