Translating Expressions

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SWBAT translate algebraic expressions.

Big Idea

Students are math translators.

Brainstorming Activity

10 minutes

For the activity, students will work with their group and brainstorm any words that represent the operations of adding, subtracting, multiplying and dividing.  Students will receive the Key Words Chart to complete.

Students may know the frequently used key words, such as sum, difference, product, quotient.  I will encourage them to think beyond these words.

After about 10 minutes, students will share out the key words that they came up with.  We will discuss any differences that students may have in their placement of words.  I will add words to the chart that students may not have thought of, such as exceeds by or loss of.  See Key Word Completed Chart for the final result.




5 minutes

Before I begin the lesson, I will share a short story to garner students' interest in the lesson.  

Every summer I like to travel.  Last summer I spent some time in Thailand.  I loved the culture, the sights, and the people.  I enjoyed the Thai food a lot too.  However, I had to be careful because I'm allergic to peanuts and peanuts are used often in Thai food.  Whenever I ate at a local restaurant I had to be sure to tell them I didn't want peanuts in my food. Unfortunately, for me, the waitstaff usually didn't speak English. I had to use a translator to communicate what I wanted.  The translator would change what I said in English to Thai.

Mini Lesson

10 minutes

This lesson will focus on translating expressions.  I will explain to students:

Today, you are math translators.  You will translate from verbal expressions to algebraic expressions.

Before I work on examples with the class, I will share an important rule of thumb that they need to remember when translating.

Important Note

If you see the words "than" or "from", reverse the order of the two items on either side of the word.

For each example, I will ask students 2 important questions to help them translate the expressions:

What is the key word?  What operation does it represent?

It may be helpful for students to underline or highlight key words.

Example 1 - Four plus a number

Example 2 - Twice a number

Example 3 - A number increased by five

Example 4 - Seven less than a number

Example 5 - Three more than a number

Next, we will move into two step algebraic expressions.  Students may have more difficulty with these, so it's important to remind them to look for the key words.

Example 6 - Seven less than the product of two and a number

Example 7 - Thirty five more than the quotient of a number and three

Example 8 - Six times a number minus twelve equals nineteen

Example 9 - Twice the difference of three and a number

Independent Practice

15 minutes

For the independent practice, students should have their Key Word Chart available as they work. 

Independent Practice

1) Twice a number minus four is sixteen

2) Nine times a number plus eight

3) Four less than the quotient of a number and two

4) Five times the sum of a number and one

5) Three times the difference between a number and ten

 After 5 minutes, students will compare their expressions to those of their groups.  If groups can't agree on an answer, we will discuss the expression as a class.


Lesson Review

5 minutes

For the lesson summary, I will pose the following question:

When choosing a variable, there are some that are often avoided:  I, i, o, s

Why are these less common?


Students should realize that these variables can often be confused with numbers.  I will suggest that they use other variables, besides these, when translating expressions.