Mathematical Symbols

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Objective

SWBAT explain what the plus and minus mean. SWBAT identify which mathematical symbol they need to represent the problem.

Big Idea

Students tackle MP.2 "Reason abstractly and quantitatively" as they learn what a number sentence is and what the symbols + and - mean!

Setting Up the Learning

5 minutes

Watch the video to see how I set kids up for learning in this lesson!

Notice our hand motions that help students remember what put together and take away mean. New research suggests that students who use their hands to gesture when learning math concepts gain a deep understanding of the problems they are taught.

In addition to drawing on the power of gesture, you'll also see that I wanted to draw on students’ existing schema, so I connected “sentences” with the new term, “number sentences”.

 

 

 

Opening Discussion

15 minutes

Don’t forget your thinking job is to figure out what the action is in the problem-

are we putting together or taking away?

Present Problem: 

The principal went to the shop and put 6 soccer balls in her shopping basket. 

Then she put 4 more soccer balls in her shopping basket. 

How many soccer balls did she put in her basket in all? 


Turn and Talk: Is this problem a put together or take away problem? How are you sure?
Guiding Questions:

  • At the end of this story, what will happen to how many soccer balls she has?
  • Will she have more soccer balls then she did at the beginning or less? 

 

I'll have students act out the problem with a partner using cubes before we move on to writing the equation.

After acting out, I'll do a quick think aloud:

"We put together two groups of soccer balls. So we are going to have to use a + sign, because we say, “put
together plus. Watch how I write the number sentence to match:

First I had 6 balls, so I will write a 6. Then I get more, I put more with the 6. So I am going to write a +. I got 4
more, so I’ll write a 4, and at the end that was the same thing as having 10, so I will write = 1"

Student Work Time and Strategy Share

15 minutes

Present next problem:

The principal had 10 soccer balls in her basket. She gave away 4 balls to Coach. How many soccer balls does she still have?

Turn and talk to your partner: What is the action of this problem? Are we putting two groups together or are we taking away?

After students discuss the problem with a partner, they will spend 5-7 minutes solving and representing the problem. During this time, I’ll push students to write a + or – to tell me which symbol represents the story.

Strategy Share:

I’ll share what one student does with cubes because this is the most basic of the strategies-“direct modeling” or acting it out.

After sharing the strategy, I’ll have students explain to a partner how this student solved the problem.

Focus Question: Do I use a + or – sign to represent this problem? How are you sure?

I’ll quickly model how to write the whole equation before students go off to do problems on their own.

Independent Practice

15 minutes

Students solve 2 word problems at desks. Each group has a different number set based on ability (see below), but all groups are expected to be able to show which symbol represents the story.

 

Group A: Intervention

Students solve problems with numbers to 10 and circle the + or -.

 

Group B: On Track

Students solve problems with numbers to 15 and circle the + or -.

 

Group C: Extension

Students solve problems with numbers to 30 and write the matching equation using the correct symbol.

 

See attached documents for independent practice! I left the numbers out of the story problems so teachers can write in the numbers that work best for their students. 

Closing

10 minutes

I will bring students back together and share 1-2 strategies that students used for problems today! I'll make sure to end the discussion of these strategies by having students help me write the number sentence that matches the story.