We have worked a lot on addition and the counting-on strategy. So far, each problem we have solved looks like this: 6 + 8 = ___, where the missing number or unknown number is after the equal sign. Today we are going to try to solve some problems where the unknown is in another part of our math problem. Sometimes the unknown number is one of the addends. Addends are the numbers you add together in an addition problem.
We have worked a lot on addition and the counting-on strategy. So far, each problem we have solved looks like this: 6 + 8 = ___, where the missing number or unknown number is after the equal sign. Today we are going to try to solve some problems where the unknown is in another part of our math problem. Sometimes the unknown number is one of the addends. Addends are the numbers you add together in an addition problem.
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
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Mathematics Teacher`s Guide primary 2
Math primary 2 first term lesson 17
Learn (40 minutes)
Learn (40 minutes)
Directions
Directions
Note to the Teacher: For the Learn section today, you will Model how to solve addition problems with an unknown in any position. Students will begin by finding the unknown in the second position.
TEACHER DO: Display the poster showing 7 hearts.
TEACHER SAY: I drew 7 hearts on my paper. When I was not looking, someone came along and drew more hearts on my paper.
TEACHER DO: Take down the poster showing 7 hearts and replace it with the poster showing 12 hearts (or cover the 7-heart poster with the 12-heart poster).
TEACHER SAY: Now there are 12 hearts. I do not know how many hearts were added to this group, but I know that all together, there are now 12 hearts. I started with 7 hearts. My mysterious friend added some hearts. Now I have 12 hearts. How could I write a number sentence to show this as an addition problem? Think quietly for a moment.
STUDENTS DO: Think quietly about how they would write a number sentence to match the story problem.
TEACHER SAY: Turn and Talk to your Shoulder Partner about how you would write the addition 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 7 + _____ = 12. Write the number sentence on the board.
TEACHER SAY: Yes, I started with 7 hearts (point to 7). Someone came along and added some hearts, but I do not know how many (point to the blank). I ended up with 12 hearts in all (point to 12). 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 addend.
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 7 hearts, and we have to count up to 12, because 12 is the sum of 7 and our unknown number. One way to solve the problem and figure out the missing number is to count on from 7 to 12. As I count on, I will hold up fingers. Count with me.
TEACHER DO: Count on from 7 to 12, holding up one finger for each number. You should be holding up 5 fingers when you reach 12.
STUDENTS DO: Count aloud with the teacher.
TEACHER SAY: We counted 5. Let’s check our work. Does 7 + 5 = 12?
STUDENTS DO: Check work to see if 7 + 5 = 12.
TEACHER SAY: Yes. We are correct. So 5 is our missing addend.
TEACHER DO: Write 5 in the blank in the equation on the board.
TEACHER SAY: Give yourself a high five if you had figured that out.
STUDENTS DO: Give themselves a high five.
2.TEACHER SAY: Th at was tough. Great thinking. Let’s try another one in your student book. Turn to the page Lesson 17: Apply. On this page, you will see some stars. At 8 p.m., Omar saw 3 stars in the sky. At 9 p.m., he saw 13 stars in the sky. How many stars were added to the sky between 8 p.m. and 9 p.m.?
TEACHER DO: Repeat the problem if necessary.
TEACHER SAY: Give me a Thumbs Up if you know what the addition sentence would look like for this problem.
STUDENTS DO: Give a Thumbs Up to volunteer. Selected students share their answers.
TEACHER DO: Write 3 + _____ = 13 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 one of the mental math strategies you have been practicing.
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.
TEACHER SAY: Who used the counting-on strategy to find the missing addend?
STUDENTS DO: Raise hands if they counted on to solve the problem.
TEACHER DO: Select students to demonstrate how they solved the problem and explain their thinking.
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 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: I am so excited about all of the wonderful math thinking I heard today. We will practice solving more problems tomorrow.
