We have worked a lot on subtraction. But so far, each problem we have had looks like the problem on the board, where the missing or unknown number is after the equal sign. Yesterday we solved addition problems where the missing number was before the equal sign. Today we are going to solve subtraction problems where the missing number is before the equal sign.
Math4u grade 2 first term
لشراء كتاب ماث فور يو جريد 2 أضغط هنا
ولمشاهدة شرح دروس ماث جريد 2 الترم الاول المنهج الجديد بأسلوب سهل وبسيط أضغط على الرابط التالى
ولمشاهدة شرح دروس ماث جريد 2 الترم الاول المنهج الجديد بأسلوب سهل وبسيط
أضغط على الرابط التالى
Mathematics Teacher`s Guide primary 2
Math primary 2 first term lesson 18
Learn (40 minutes)
Learn (40 minutes)
Directions
Directions
Note to the Teacher: For the Learn section today, you will Model how to solve subtraction problems with an unknown in the second position.
1.TEACHER DO: Write 15 – 6 = _____ on the board.
TEACHER DO: Display poster showing 15 smiley faces.
TEACHER SAY: Help me count the smiley faces.
STUDENTS DO: Count the smiley faces aloud as the teacher points.
TEACHER SAY: Thank you. I have 15 smiley faces. Someone came along and took away some of my smiley faces.
TEACHER DO: Take down the poster showing 15 smiley faces and replace it with the poster showing 9 smiley faces (or cover up the first poster with the second poster).
TEACHER SAY: Help me count again, please.
STUDENTS DO: Count the smiley faces aloud as the teacher points.
TEACHER SAY: Now I only have 9 smiley faces. I do not know how many smiley faces were taken away from this group, but I know that I started with 15 and now I have 9. How could I write a number sentence to show this as a subtraction problem? Think quietly for a moment.
STUDENTS DO: Think quietly about how they would write the subtraction problem.
TEACHER SAY: Turn and Talk to your Shoulder Partner about how you would write the subtraction problem. See if you agree or disagree.
STUDENTS DO: Talk to their Shoulder Partners.
TEACHER SAY: Give me a Thumbs Up if you have an idea you would like to share.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students share their answers at the board.
TEACHER DO: Confirm or provide the correct answer 15 – _____ = 9. Write the number sentence on the board.
TEACHER SAY: Yes, I started with 15 smiley faces (point to 15). Someone came along and took some smiley faces, but I do not know how many (point to the blank). I ended up with 9 smiley faces in all (point to 9). How would you figure out what number should go in the blank? Think quietly for a moment.
STUDENTS DO: Think quietly about how they would figure out the missing number.
TEACHER SAY: Turn and Talk to your Shoulder Partner about how you would figure out the missing number. See if you agree or disagree.
STUDENTS DO: Talk to their Shoulder Partners.
TEACHER SAY: Give me a Thumbs Up if you have an idea you would like to share.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students share their strategies.
TEACHER DO: Listen to students’ answers. Confirm all strategies that would give students the correct missing number. If any students describe the Counting On strategy, focus instruction on that. If no students describe the Counting On strategy, introduce the idea to students. Adjust the following section as needed.
TEACHER SAY: We know we have 15 smiley faces, and we have to count on from 9. That will tell us how many smiley faces were subtracted from 15 to give us 9. As I count on, I will hold up fingers. Count with me.
TEACHER DO: Count on from 9 to 15, holding up one finger for each number. You should be holding up 6 fingers when you reach 15.
STUDENTS DO: Count aloud with the teacher.
TEACHER SAY: We counted 6. Let’s check our work. Does 15 – 6 = 9?
STUDENTS DO: Check work to see if 15 – 6 = 9.
TEACHER SAY: Yes. We are correct. So 6 is our unknown.
TEACHER DO: Write 6 in the blank in the equation on the board.
TEACHER SAY: Give yourself a pat on the back if you had figured that out.
STUDENTS DO: Give themselves a pat on the back.
2.TEACHER SAY: Th at was tough, but you did it. Let’s try another one in your student book. Turn to the page Lesson 18: Apply.
STUDENTS DO: Turn to Lesson 18 in their student book.
TEACHER SAY: On this page you will see some candies. Before lunch, Aya had 20 candies. After lunch, Aya had 11 candies left. How many candies did Aya eat at lunch?
TEACHER DO: Repeat the problem if necessary.
TEACHER SAY: Give me a Thumbs Up if you know what the subtraction sentence would look like for this problem.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students share their answers.
TEACHER DO: Confirm or provide the correct answer. Write 20 – _____ = 11 on the board. Direct students to copy the problem into their student books.
STUDENTS DO: Write the equation in their student books.
TEACHER SAY: Work with your Shoulder Partner to figure out the missing number in the equation. Use the Counting On strategy. You have about 2 minutes.
STUDENTS DO: Work with Shoulder Partners to solve the problem in their student books.
TEACHER DO: Walk around the room and observe students as they work. Listen to their conversations and note which students are using strategies that will not work. After about 2 minutes (or when most students are finished), use an Attention Getting Signal. Select students to demonstrate how they solved the problem and explain their thinking.
STUDENTS DO: Selected students demonstrate and explain how they used the Counting
On strategy to solve the problem. Seated students observe and ask questions.
TEACHER DO: Ask for students who used a different strategy and have them Model their solutions.
STUDENTS DO: Selected students demonstrate and explain how they used a mental math strategy to solve the problem. Seated students observe and ask questions
TEACHER SAY: You are amazing thinkers. I enjoy hearing you talk about your strategies and seeing you help each other learn.
