solve addition story problems involving mass - math grade 2 - lesson 53

Today we are going to solve story problems involving mass. We will do one together, and then I will ask you to work with a partner to solve some problems in your student books.

Note to the Teacher: In today’s lesson, you Model how to solve one-step story problems involving mass. Students work with a partner to solve several one-step story problems using picture clues. Th is activity reinforces their addition skills and provides a review of the mass of diff erent objects.

1.TEACHER SAY: Yesterday I gave you an assignment to do at home. I asked you to fi nd an object at your house, draw it, and write its mass (or estimated mass) on the paper. Raise your hand if you were able to do the project.

STUDENTS DO: Raise hand if they did the project.

TEACHER DO: If many students completed the project, collect the papers and do a Gallery Walk. If few students completed the project, have those students present their fi ndings to the class.

STUDENTS DO: Participate in Gallery Walk to view their friends’ work or share their work with the whole group.

TEACHER SAY: Great work. You may go back to your seat now.

STUDENTS DO: Go back to their seat.

TEACHER DO: Gather the 5 bags of rice with 1 kilogram labels and put them at the front of the room in two groups: one group of 3 and one group of 2.

TEACHER SAY: Fatima has 3 bags of rice. Hassan has 2 bags of rice. Each bag has a mass of 1 kilogram. How many kilograms of rice do they have in all? Think about the story problem. What are we trying to find out?

STUDENTS DO: Say: How many kilograms of rice in all.

TEACHER SAY: Yes, they want us to find how many kilograms of rice there are all together.

 What information do we have? I will use Calling Sticks to select some of you to identify the information provided in the story problem.

STUDENTS DO: Selected students share information provided in the story problem. Answers should include: each bag of rice has a mass of 1 kilogram, Fatima has 3 bags of rice, Hassan has 2 bags of rice.

TEACHER SAY: Stand up if you think you know the answer to the problem.

STUDENTS DO: Stand if they know the answer.

TEACHER DO: Call on a standing student to solve the problem and explain their strategy.

STUDENTS DO: Selected student provides the answer and explains how they solved the problem.

TEACHER DO: Write the addition sentence on the board: 3 kg + 2 kg = 5 kg.

TEACHER SAY: Remember we can use the letters kg to stand for kilograms. Give yourself a pat on the back if you had 5 kilograms as the answer.

STUDENTS DO: Pat themselves on the back.

TEACHER SAY: What letter we can use to stand for gram?

STUDENTS DO: Respond together: gm.

TEACHER SAY: Good. The problems you solve in your student book will be more challenging than the problem we just did. Take out your student book and turn to page Lesson 53: Apply.

STUDENTS DO: Open student book to page Lesson 53: Apply.

TEACHER DO: Place students in groups of 3 or 4, making sure there is at least one strong reader in each group to read the story problems. Those students will be the group “reader.” Have students move to work with their groups.

STUDENTS DO: After being placed in a group, move to a quiet spot in the classroom. Selected students will be the group reader.

TEACHER SAY: Each group will have one reader. I will tell each group who their reader is today. The reader will read a story problem aloud. Then each person in the group will work by themselves to solve the problem. When everyone in the group is finished with the first problem, the reader will read the next problem aloud.

TEACHER DO: Tell each group who the reader is for today.

TEACHER SAY: There are four different story problems. Write the addition problem, solve it, and write your answer. Do not forget to write gm or kg after your answer.

STUDENTS DO: Listen to the reader read each problem aloud, and then solve the one-step story problems on their own.

TEACHER DO: As students are working, circulate around the room, off ering help as needed. Allow students time to solve the problems. If time allows, use Calling Sticks to select students to work out the problems on the board. Otherwise, go over the correct answers with students.