There Must Be Order!
Students will evaluate numerical expressions that use parentheses, brackets, or braces.
Introduction (10 minutes)
- Have students write "PEMDAS" across the top of their papers. Have them write the meaning behind each letter of the acronym next to, on top of, or below each letter.
- Tell students that they will use this as a checklist when they solve equations. Students may need your help to get started.
- Give students a simple mathematical expression like (25–11)x3.
- Ask students to start with the letter “P” and first work the expression in parenthesis:(25–11) x 3 = 14x3.
- Then ask students if they can identify any Es. They should say no.
- Ask them to solve any Ms: 14x3 = 42
- Next, ask them are there any Ds, As, or Ss? They should say no.
- Advise them that they just used the order of operations to solve this expression.
- Explain that today’s lesson is going to require them to use the order of operations to solve mathematical equations that have parenthesis, braces, and brackets which are tools used in math to group equations.
Explicit Instruction/Teacher Modeling (15 minutes)
- Remind students that they have had practice with orders of operations before, and with a little practice now these memories will come back.
- Tell students that the reason the rules are there for solving these expressions is because order does matter in finding the final answer.
- Use a few problems from the Order of Operations Puzzle worksheet to demonstrate what happens when you do not follow the order of operations.
Guided Practice/Interactive Modeling (25 minutes)
- Project the There Must Be Order worksheet onto the board.
- Have students use their order of operations checklist to complete the worksheet as they follow along with you.
- Allow students to interact with the whiteboard as they develop new understandings.
- Answer student questions and call on students randomly to ensure students are developing an understanding of the concept.
Independent Working Time (45 minutes)
- Pass out blank paper.
- Have the students write four problems on this sheet of paper.
- Tell students that one problem has to have parenthesis, one problem has to have brackets and parenthesis, one problem has to have at least one exponent and the last problem has to include parenthesis, brackets, braces, and an exponent.
- Have students solve their own problems.
- Ask students to work alone, but if students have questions, allow them to peer tutor each other.
- Remind students to use their PEMDAS checklists as they work through the independent practice.
- Enrichment: Have students create a set of questions and answers that include brackets, braces, decimals, and fractions.
- Support: Have students come up with a phrase such as “Please Excuse My Dear Aunt Sally” to help with remembering the PEMDAS acronym.
Assessment (20 minutes)
- Give students the following equation: [(5 x 50) - 10)]3 + (4 x 3).
- Have them solve it step by step identifying and using the PEMDAS acronym.
Review and Closing (5 minutes)
- Have students explain again what PEMDAS is and when they use it.
- Recap what students learned during this lesson.
- Have students turn to a partner and tell them one place they might see these types of problems in the real world.