Yesterday we decomposed numbers to solve addition story problems. Today we are going to use the same strategy to solve 2 two-digit subtraction story problems without regrouping.
Yesterday we decomposed numbers to solve addition story problems. Today we are going to use the same strategy to solve 2 two-digit subtraction story problems without regrouping.
Math4u grade 2 first term
ماث فور يو جريد 2
math grade 2 first term
math grade 2 first term
شرح دروس ماث جريد 2 الترم الاول المنهج الجديد بأسلوب سهل وبسيط
شرح دروس ماث جريد 2 الترم الاول المنهج الجديد بأسلوب سهل وبسيط
Mathematics Teacher`s Guide primary 2
Math primary 2 first term lesson 35
Learn (40 minutes)
Learn (40 minutes)
Directions
Directions
1.TEACHER SAY: We will do one together, and then you will work with a partner to solve some on your own.
TEACHER DO: Write a blank subtraction sentence on the board, along with a Tens–Ones chart and a Tens–Ones boxes diagram.
TEACHER SAY: Here is our first story problem. Sabra made 37 falafel balls with his mother. For dinner that night, they ate 25 falafel balls. How many falafel balls were left? Let's write a math sentence for that story problem. What is the first number we should write? Why?
TEACHER DO: Use Calling Sticks to select students to help. If students are not sure, remind them that the biggest number goes first in subtraction problems and that Sabra and his mother started with 37 falafel balls. Ask a student to help you write the sentence 37 – 25 = ___ on the board.
TEACHER SAY: When we subtract, we do not actually need to decompose both numbers. We can decompose the bigger number, then take some away from that number to find the difference. I will show you what that looks like.
TEACHER DO: Model using the Tens sticks and Ones dots to decompose the number 37. Have students help you, if possible. Draw 3 Tens sticks and 7 Ones dots, then remove or cross out 2 Tens sticks and 5 Ones dots. Make sure students understand you are subtracting the Tens and Ones in the second number.
TEACHER SAY: We can also use our Tens and Ones boxes to help us decompose. Watch as I Model this strategy.
TEACHER DO: Model how to use the Tens and Ones boxes to decompose 37. Have students help you, if possible.
TEACHER SAY: To solve the subtraction problem using the Tens and Ones boxes, we subtract
the Tens and then we subtract the Ones. We have 3 Tens, or 30. We need to subtract 2 Tens, or 20. Give me a Thumbs Up if you know the answer to 30 – 20.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students answer the question.
TEACHER DO: Confirm the correct answer if offered by a student. Then write 30 – 20 on the board and Model how to mentally subtract tens.
TEACHER SAY: When we subtract 20 from 30, we can count back by tens. If we start at 30 and count back 2 tens—30, 20, 10—we get 10.
TEACHER DO: Draw another set of Tens and Ones boxes under the answer blank. Write 10 in the Tens box.
TEACHER SAY: We also have to subtract Ones: 7 – 5. Show me on your hands what 7 – 5 is.
STUDENTS DO: Show the difference on their hands.
TEACHER SAY: Yes, 7 – 5 is 2.
TEACHER DO: Write 2 in the Ones box under the answer blank.
TEACHER SAY: Look at the Tens and Ones boxes for the answer. It has 1 Ten and 2 Ones, so the difference is 12. Twelve falafel balls were left. Yum.
TEACHER DO: Complete the problem on the board. Completed problem should look like this:
2.TEACHER SAY: I am wondering what questions you have about doing subtraction story problems before you try some on your own.
STUDENTS DO: Ask questions if they have any.
TEACHER DO: Answer students’ questions or allow students to respond to and help each other.
TEACHER SAY: Now it is time for you to try a subtraction story problem on your own. You will work at your desk with your Shoulder Partner. Take out your student book and turn to page Lesson 35: Apply.
STUDENTS DO: Turn to page Lesson 35: Apply in the student books.
TEACHER SAY: In your student book, you will see the story problem we just solved and three more story problems. I will read each story problem aloud. For each problem, there is a Tens–Ones chart and Tens–Ones boxes. Work with your Shoulder Partner to decompose the problems both ways and find the differences. Be sure to show your work. Put your finger on the first story problem and read it with me as I read it aloud. Rashida had 26 dates. She gave 13 to her sister. How many dates does Rashida have left?
TEACHER DO: Depending on your students, read only the first story problem or all three.
TEACHER SAY: First, write down the numbers from the problem. Th en you may begin decomposing and subtracting.
STUDENTS DO: Work with their Shoulder Partner to decompose numbers and solve the subtraction story problems in the student books.
TEACHER DO: Walk around the classroom to assist students as needed. Allow time for students to solve and check their work. Take note of students who may need additional instruction and support. If time allows, call a student to the front to share their work. Repeat with the other story problems in the student book.
TEACHER SAY: Th at was great work, class. I appreciate it when you work together to solve problems and help each other.
TEACHER DO: Write a blank subtraction sentence on the board, along with a Tens–Ones chart and a Tens–Ones boxes diagram.
TEACHER SAY: Here is our first story problem. Sabra made 37 falafel balls with his mother. For dinner that night, they ate 25 falafel balls. How many falafel balls were left? Let's write a math sentence for that story problem. What is the first number we should write? Why?
TEACHER DO: Use Calling Sticks to select students to help. If students are not sure, remind them that the biggest number goes first in subtraction problems and that Sabra and his mother started with 37 falafel balls. Ask a student to help you write the sentence 37 – 25 = ___ on the board.
TEACHER SAY: When we subtract, we do not actually need to decompose both numbers. We can decompose the bigger number, then take some away from that number to find the difference. I will show you what that looks like.
TEACHER DO: Model using the Tens sticks and Ones dots to decompose the number 37. Have students help you, if possible. Draw 3 Tens sticks and 7 Ones dots, then remove or cross out 2 Tens sticks and 5 Ones dots. Make sure students understand you are subtracting the Tens and Ones in the second number.
TEACHER SAY: We can also use our Tens and Ones boxes to help us decompose. Watch as I Model this strategy.
TEACHER DO: Model how to use the Tens and Ones boxes to decompose 37. Have students help you, if possible.
TEACHER SAY: To solve the subtraction problem using the Tens and Ones boxes, we subtract
the Tens and then we subtract the Ones. We have 3 Tens, or 30. We need to subtract 2 Tens, or 20. Give me a Thumbs Up if you know the answer to 30 – 20.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students answer the question.
TEACHER DO: Confirm the correct answer if offered by a student. Then write 30 – 20 on the board and Model how to mentally subtract tens.
TEACHER SAY: When we subtract 20 from 30, we can count back by tens. If we start at 30 and count back 2 tens—30, 20, 10—we get 10.
TEACHER DO: Draw another set of Tens and Ones boxes under the answer blank. Write 10 in the Tens box.
TEACHER SAY: We also have to subtract Ones: 7 – 5. Show me on your hands what 7 – 5 is.
STUDENTS DO: Show the difference on their hands.
TEACHER SAY: Yes, 7 – 5 is 2.
TEACHER DO: Write 2 in the Ones box under the answer blank.
TEACHER SAY: Look at the Tens and Ones boxes for the answer. It has 1 Ten and 2 Ones, so the difference is 12. Twelve falafel balls were left. Yum.
TEACHER DO: Complete the problem on the board. Completed problem should look like this:
2.TEACHER SAY: I am wondering what questions you have about doing subtraction story problems before you try some on your own.
STUDENTS DO: Ask questions if they have any.
TEACHER DO: Answer students’ questions or allow students to respond to and help each other.
TEACHER SAY: Now it is time for you to try a subtraction story problem on your own. You will work at your desk with your Shoulder Partner. Take out your student book and turn to page Lesson 35: Apply.
STUDENTS DO: Turn to page Lesson 35: Apply in the student books.
TEACHER SAY: In your student book, you will see the story problem we just solved and three more story problems. I will read each story problem aloud. For each problem, there is a Tens–Ones chart and Tens–Ones boxes. Work with your Shoulder Partner to decompose the problems both ways and find the differences. Be sure to show your work. Put your finger on the first story problem and read it with me as I read it aloud. Rashida had 26 dates. She gave 13 to her sister. How many dates does Rashida have left?
TEACHER DO: Depending on your students, read only the first story problem or all three.
TEACHER SAY: First, write down the numbers from the problem. Th en you may begin decomposing and subtracting.
STUDENTS DO: Work with their Shoulder Partner to decompose numbers and solve the subtraction story problems in the student books.
TEACHER DO: Walk around the classroom to assist students as needed. Allow time for students to solve and check their work. Take note of students who may need additional instruction and support. If time allows, call a student to the front to share their work. Repeat with the other story problems in the student book.
TEACHER SAY: Th at was great work, class. I appreciate it when you work together to solve problems and help each other.
