Lesson 1-1 Variables and Expressions

Today we will begin actually learning math. No more testing!!! (at least for a little while) We will be learning about how to use variables and expressions.

Variables and expressions are the basic building blocks of algebra. It is very important to understand these key concepts as we move on into a little higher math.

Vocabulary:

Variables: these are the symbols such as x, y, or any other letter or picture we use to express a number that we do not know the value of. We call them variables because they could mean many different numbers

Expressions: these are the mathematical representations of a sentence dealing with values.

Numerical Expressions: these are expressions that only involve numbers

Variable Expressions: these are expressions that involve both variables and numbers


It is important that we can change these sentences into expressions and expressions into sentences. It is very hard to apply them into every day life if you don't know how to use them.

Here is an example of turning a sentence into a numerical expression:

Ex.1 5 groups of 7 and 2 more

In math, we use symbols such as +, -, *, and / to show what we are trying to say with words.

There are key words that allow us to understand what we need to do. In the example above, "groups of" lets us know we are talking about multiplication and the word "and" and "more" tells us that we need to add.

5 groups of 7 and 2 more

Our numerical expression would be this:

5*7 + 2


We can do the same thing with a variable expression. we just have to use a variable in place of a number.

Ex. 2. one less than twice the value of b

Once again, we pick out the key words but we also pick out the variable. In this example, b will be the variable because we do not know what b is. The key words from this is " less" meaning to take away or subtract, and "twice the value" meaning that it is multiplied by 2.

One less means minus one. Twice the value of b tells us that b is multiplied by 2. If we put this together mathematically it would look something like this.

2b -1

We will have lots of practice with this tomorrow.

Here is the homework worksheet for Wednesday.

Variables and Expressions