At Mach 3 the SR 71’s titanium skin expanded several inches as temperatures spiked above 3,000 degrees on leading edges. Designers developed movable inlet cones, specialized fuel, and heat-resistant ...

An algebraic equation contains one or more letters in it. Each letter in the equation is called a variable. A variable can change in value. We guess at different values for each letter until our ...

Simultaneous equations are two linear equations that can be solved using bar models. By remembering that the same letter will always have the same value we can work out the missing values. To solve ...

David lives in Brooklyn where he's spent more than a decade covering all things edible, including meal kit services, food subscriptions, kitchen tools and cooking tips. David earned his BA from ...