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Students will apply addition strategies to solve three-digit, two-step word problems.
- Invite students to sit in a circle and distribute a mixture of addition and subtraction flashcards, giving one card per student.
- Tell the students that their task is to go around the circle and add or subtract as quickly as possible, using the number that their neighbour calculates.
- Tell the students that the starting number is 250.
- Ask one student to begin and give students the opportunity to go around the circle, adding or subtracting to the previous number that was spoken.
- Note that there were many steps in achieving the final answer. Explain that some word problems involve more than one step in order to find the solution and that they will be learning how to solve two-step word problems.
Explicit Instruction/Teacher modeling(10 minutes)
- Write the following problem on the board: Jen opened her bakery shop on Tuesday morning with 215 chocolate chip cookies. That morning, she baked 250 more chocolate chip cookies. During the day, customers came into her shop and bought 130 of those cookies. How many chocolate chip cookies did she have in her shop at the end of the day?
- Tell the students that you are going to show them how to find words in the word problem that can help you know how to solve the problem.
- Demonstrate the process of underlining the words “baked” and “bought.”
- Thinking aloud, show the students the starting number of 215 cookies. Then, show the students how you can figure out that the word “baked” means that Jen is adding more cookies to her original number of cookies.
- Model the process of adding the two numbers. Tell the students that they can use any addition strategy to add those numbers.
- Continue to the word “bought” and think aloud, telling the students that when customers bought the cookies they were taking them from the shop, which meant that there were fewer cookies. Tell the students that you are now going to subtract. Model the subtraction.
- Reread the final question aloud and tell the students that since it doesn’t say that Jen baked any more cookies, then that must have been the final amount at the end of the day.
- Show the students your final answer.
Guided practise(10 minutes)
- Distribute one pair of +/- cards to each student, along with an individual whiteboard and whiteboard marker.
- Write the following problem on a whiteboard or show it on the SMARTboard: “When Susie first opened her shop she had 425 donuts left over from the previous day. Some customers came in and bought 115 donuts. Susie made 325 more donuts. How many donuts did Susie have at the end of the day?”
- Ask the students to share what word in the problem gives a clue about Susie’s donuts at the beginning of the day.
- Next, ask the students to share the word that shows what happened next.
- Invite students to hold up the sign (addition or subtraction) that matches the action of the customers that bought the donuts.
- Ask the students to show their work for the first part of the problem on their whiteboards.
- Continue with the second part of the problem and invites students to share the clue word and to show either an addition or subtraction sign to match the word.
- Ask the students to find the answer to the problem on their whiteboards.
Independent working time(15 minutes)
- Ask the students to complete the worksheet, Karen’s Busy Bakery.
- Assist students, as needed.
- Challenge students to write their own two-step word problems and trade with a partner.
- Use colour coding or highlight sections of word problems on the worksheet in advance.
- Allow students to create a sequence of illustrations that represents the actions found in the story problem. Challenge the students to consider if the actions show a need for addition or subtraction.
- Invite students to create digital representations of the actions represented in the word problems that show the operations used in the problems.
- Use Kahoot, Quizlet, or another online game creator to quiz students on what operations (addition or subtraction) they would use.
- Ask students to choose a problem from the worksheet and write a short explanation for how they solved the problem. Challenge students to explain their thinking.
Review and closing(5 minutes)
- Invite students to share with a partner how they can use multiple steps to solve problems. What are some examples of addition and subtraction that require two steps in real life?
- Ask students to reflect on the first activity you did with flashcards. Why would a teacher choose that activity to get you warmed up for this lesson?