SWBAT use addition and subtraction within 20 to solve word problems.

What is going on? I want my students to figure out what is the word problem for the answer given. This provides them with an opportunity to think backwards to solve and adds to their experiences with problem-solving.

5 minutes

The mental process of discovering, analyzing, and solving problems is an important life skill for students to develop and is strongly supported by the CCSS. My students have been developing multiple strategies to solve addition and subtraction and using models to assist in transitioning from concrete thought cycles to more abstract, quantitative thinking (MP2). The most important piece of solving problems with addition and subtraction for my students at this point is the ability to see those pieces broken apart and understand the part-part-whole relationship (1.OA.A.1). I want them to use the models we have practiced, e.g., objects, drawings, or symbols, to solve problems requiring adding to, taking apart, putting together, and comparing. Today's lesson will have them thinking about all of these concepts as they develop their own word problems.

We will get our thought processes warmed up by playing a game of classroom "I Spy."

*Students lets go to the carpet and sit in our spots. We are going to play I Spy and everyone will get a turn to answer. *

*I spy something brown, shaped like a rectangle and we sit at it.* (Our desk)

I will continue the game until everyone gets a turn.

10 minutes

I will start with my beginning problem and intro the concept to my students that we are creating our own problems for today's lesson. I will write the following on the board:

**The answer is 4 horses.**

Then, I will explain to them that they are going to be the ones to create the word problem that will result in this answer. Discussion points will include:

*If we want this problem to be subtraction we must start with a larger number and have some horses go away.**If we want this problem to be addition we must start with a 4 and have none join them or start with a smaller number than 4 and have some join them.*

Before I ask for answers I will ask them to turn to their neighbor and discuss their idea. What do they think would work? What kind of story could they create? I want them to bounce ideas off each other and see what makes sense. When both partners are ready, they can both raise their hand to share a story idea.

After this problem we will tackle another one together:

**The answer is 9 scoops of ice cream.**

Here you will see us solving our problem and our answer.

20 minutes

I will print the What is the problem? workbook and copy for each student. The biggest hurdle for my students is using their imagination. It is a skill we talk about and use during reading instruction, but not so much during math time. I will walk the room and provide assistance when needed, but really try to let them come up with their own problems for this practice time. You can view some completed work here and remember to try and just provide a seed for them to grow an idea from if they are stumped. This is a great learning opportunity for them to develop their own word problems that make sense.

5 minutes

I will ask my students to popcorn answer these questions:

- If we are subtracting the answer will be smaller or larger then the first number? (smaller)
- If we are adding the answer will be smaller or bigger then both the first two numbers? (bigger)

Next Lesson