3 Addends

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SWBAT use three addends to solve a problem

Big Idea

When we add 3 addends we can look for a friendly combination to make our work easier

Number work

5 minutes

I will have the students gather at the carpet area.  I will show them one number dot card for approx. 3 seconds.  If they know the total number of dots they are to give me a thumbs up.  I plan to call on students.  I will ask them first, what was the total number of dots?  Then my second question will be how did you put the dots together?   I'll then look to the whole group and ask, "Thumbs up if you put the dots together in that order?"   And secondly, "Did anyone have a different way of grouping the dots together?"  

I plan to use 5 of the subitizing cards.   (I have made copies of all the cards on cardstock and laminated them, I found 5 that I think will work for this section)  You could also make your own cards if you wanted too.  I am a HUGE fan of the Van de Walle "Teaching Student Centered Mathematics."

I want the students to think of grouping the dots together to make friendly numbers.  In the 1st grade CCSS students are to apply properties of operations as a strategy to add/subtract.  This is setting up the foundation for that.  


Mini lesson

15 minutes

For this portion of the lesson I will have students  work at their tables with unifix cubes and white boards.  I have whiteboards for my students that are approx.  11"x18".  Thank goodness for Lowes and a husband who is handy! 

I plan to orally state these problems and have students use the cubes and their whiteboards to work through and record their thinking.  I want the students to use their whiteboards because it will actively engage everyone, we want students to model with mathematics, which is one of the eight Mathematical Practices.  I want them applying their knowledge, not just copying my work.  

First problem:  

I have 7 skittles.

Bordy has 3 skittles.

Zoey has 2 skittles.  

I will ask:  How do we decide which numbers to add together first?

Ask students to think about which 2 numbers they will put together first.  How could we put these numbers together the easiest?

Will we get the same number if we solve it  different ways?

I will allow time for students to work the problems and and then as I am circulating around I'll look for students to do a quick share out.  I will be looking for 2 different ways to solve the problem.  (which means did they put the 7 and the 3 together, or the 7 and the 2 together) 

Continue on with the following number choices.  Always looking for which numbers are students putting together first.  I want to guide students to look for the friendly numbers to put together to make the work more efficient.  

Try this one:   2+3+1=   

Which numbers do you want to put together first?

5+2+3=   (do you see a friendly number you could make first)   (the 2  and the 3 to make 5)

3+4+6=  (do you see a friendly number you could make first)    (the 4 and the 6 to make 10)

7+3+1=      (the 7 and the 3 to make 10)

3+6+3         (the 3 and the 3 to make 6)

Remember these are just one way to put the numbers together, they are not the only way.  Students are coming up with their efficient strategy to apply the associative property of addition, which is a property first graders should know based on the CCSS framework for math.

Independent work

15 minutes

Students will use the worksheet and add the 3 addends.  I want them to show which numbers they put together first.  I am asking them to do this because I want to get away from looking at them as 3 numbers and just counting on.  Is there a fact the students know inside the 3 addends to help them solve the problem.   This independent activity will assess how students are putting the 3 addends together.  Are they using the Associative property of addition?  


When they are finished they are to get out their math notebook.  See the next section.  

Math Journal work

10 minutes

When the students finish up with their independent work, they are to get out their math notebook.  They will now have the opportunity to write their own 3 addend equations.  They can use any numbers 1-6.  No doubles or triples.  I am stating this because I want them to come up with their own strategy to solve their equations, not using a counting pattern or doubles fact that they already know.  

I will ask the students to check in with me.  I want them to explain their thinking.  Students need to construct viable arguments, one of the eight Mathematical Practices.  1st graders can justify their mathematical thinking.  I will ask clarify questions or guide them to a more efficient strategy.