CCSS.Math.Content.5.OA.A.2 Write simple expressions that record calculations with numbers, and interpret numerical expressions without evaluating them. For example, express the calculation “add 8 and 7, then multiply by 2” as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is three times as large as 18932 + 921, without having to calculate the indicated sum or product.
As part of the exercises to learn this standard, students wrote descriptions of school events that involve numbers and then turned the descriptions into expressions.
For example, two boys wrote a description similar to this:
Tom and Mike ride two miles every Monday, Tuesday, and Wednesday during the school year. How many miles did they ride in one school year?
Turning these words into an expression isn't easy and there's more than one way to do it.
They're working on an expression that looks something like this:
180/5 X 3 X 2 X 2
Explanation: 180 days of school divided by 5 days in a week will give you the approximate number of each day of the week during the school year. Then multiplying that # by 3 gives you the total Monday, Tuesday, and Wednesday for the year. Then multiplying that by two miles and then two again because each boy rode two miles provides you with the number of miles they rode together during the school year.
I like this activity because it truly makes math partners think about numbers and expressions, and their evaluation leads to deeper understanding about their daily events and tasks as well.
Learning about expressions by describing life's events with numbers, operations, and variables meets the content standards, standards for mathematical practice, and develops mathematical thinking in meaningful ways. Have you tried this approach? If so, please share.
