Problems with Parentheses
Students will be able to accurately solve and create number sentences with parentheses.
Introduction (5 minutes)
- Write the sentences Let’s eat Grandma and Let’s eat, Grandma on the board.
- Discuss the difference between the two sentences.
- Raise a discussion on the order of the comma. Potential discussion questions include: How does the comma change the meaning of the sentence? What are other examples of sentences you have seen that change meaning with the comma placement?
Explicit Instruction/Teacher Modeling (10 minutes)
- Explain to your students that just as the comma changes the meaning of the sentence, there is punctuation in a number model or expression that changes the outcome of the problem.
- Watch the PEMDAS video.
- Write 5 + 6 x 2 on the board, and ask your students to solve the problem.
- Add parentheses to make the problem 5 + (6 x 2), and model solving inside the parentheses first. Ask your students to turn and talk about how it changed the problem.
- Repeat with 14 / 2 + 5.
- Have half the class solve with the parentheses around ( 14 / 2 ) + 5 and the other half with 14 / ( 2 + 5 ).
- Discuss the steps students took to solve and how the answers are different.
Guided Practice/Interactive Modeling (20 minutes)
- Explain to your students that they will rearrange numbers and add parentheses to make number sentences true.
- Divide students into 4-5 groups. Have one group go at a time in front of the class. Direct the other students to help solve on scratch paper or whiteboards.
- Hand out number cards, operation cards, and parentheses cards to the first group.
- Provide them with the number answer card to their problem.
- Have students display their number cards and operation cards to the class so they can write down their options and begin solving independently.
- Ask the first group to rearrange themselves with parentheses to reach the number answer and make the number sentence true.
- Repeat with the rest of the groups.
Independent Working Time (10 minutes)
- Introduce the Lucky 13 challenge.
- Review the directions, and answer your students' questions. Remind students that they can use any of the four operations.
- Instruct your students to complete the worksheet.
- Enrichment: Direct your students to create their own challenge with four (or more) additional playing cards.
- Support: Provide playing cards so that your students can physically manipulate and rearrange the numbers.
Related Books and/or Media
- VIDEO: PEMDAS song
Assessment (10 minutes)
- During the Lucky 13 Challenge, walk around the room and make sure that your students' number sentences make sense.
Review and Closing (5 minutes)
- Have your students share one of the expressions they created to make the number 13.
- As students share, have the class check the work to make sure the number sentences are correct.