Lesson idea for order of operations

By Murray Bourne, 29 Mar 2011

Some math lessons can be a bit, shall we say, "dry". The topic "Order of Operations" would certainly fall into that category.

This topic includes gems like BODMAS (brackets first, then divisions and multiplications as you come to them from left to right; finally additions and subtractions as you come to them from left to right).

Here's an alternative way to get students involved in this topic. It's based on a submission by Sunil Singh in the Escape the Textbook community (quoted in NaturalMath).

The Lesson

Give out a sheet of paper which has the numbers 1 to 24 down the left-hand column. 

Students have to construct an operations question using just the numbers 1, 3, 4 and 6 to produce each one of the numbers 1 to 24. Only addition, subtraction, multiplication, division and brackets can be used. 

No "fancy" operations like exponents and factorials, or concatenation of the numbers (you can't write "34" as one of the numbers) are allowed.

Each number has to be used exactly once. 

To start, get students to suggest some basic operations with the 4 allowed numbers and see what you get. For example:

1 + 3 + 4 + 6 = 14

6 × 4 − 3 − 1 = 20

(6 + 1) × (4 − 3) = 7

You get the idea. 

Try this with your class next time the Order of Operations topic comes up (or when you have an "activities" lesson planned).

Tell me how it goes.

See the 3 Comments below.

3 Comments on “Lesson idea for order of operations”

  1. Sue says:

    I have done this activity with my junior maths class and it works. Order of Ops is very dry u r correct but doing this provides a challenge. Also when all gathered at the end of the lesson I ask students to read out their sums and which number they think their sum makes. Many students do not use brackets or order of ops correctly when written but work it out verbally to give their answer. Misconception found!! Easy to tell them how to correct their maths equation to make it match the verbal one read out!! Really good stuff.

  2. Murray says:

    Thanks for the story, Sue. Glad it works for you!

  3. Peter Price says:

    Great idea, Murray. So much better than teaching starting from the rules, which as you note is very 'dry'.

    This is a good example of a strategy based on students seeing the need for facts to be learned before introducing said facts to them.

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