2c. Evaluate expressions at specific values of their variables. Include expressions that arise from formulas used in real-world problems. Perform arithmetic operations, including those involving whole-number exponents, in the conventional order when there are no parentheses to specify a particular order (Order of Operations). For example, use the formulas V = s³ and A = 6s² to find the volume and surface area of a cube with sides of length s = ½.

At first glance, this standard sounds way more involved than it actually is. Seriously? "Evaluate," "expressions," "values," "variables," "formulas," "real-world problems," "arithmetic operations," "whole-number exponents," and "Order of Operations"? It's got more math terms than we know what to do with. We'll probably just do what we always do: claim them as our own and then sell them on eBay for a profit.

In practice, all the parts of this standard are essentially saying two very similar things. First, students should be able to perform arithmetic operations (i.e., addition, subtraction, multiplication, division, and whole-number exponentiation) on numerical expressions. That means being able to successfully complete these operations in the right order—whether that order is determined by parentheses or PEMDAS.

Second, students should realize that evaluating an expression at a given value just means they should plug in the given value into the expression whenever they see that variable. In other words, finding 3 – a when a = 2 just means substituting 2 for a in the expression to get 3 – 2, or 1. Blam-o!

Sure, we'll use expressions from real-world formulas. Sure, we'll use expressions involving whole-number exponents. Sure, we'll make the expressions slightly more complicated than 3 – a—but what we're asking students to do is exactly what we've already mentioned: plug a given value into an expression and evaluate it. Simple as that.