Number Stories!

During the second quarter, first graders have been solving word problems that involve addition, subtraction, and missing addends.  Word problems (or number stories, as we sometimes call them) can be tough!  They combine reading, critical thinking, and modeling to solve problems.  But they can also make abstract concepts like addition and subtraction more concrete by requiring students to apply their knowledge of mathematical relationships in real world settings. 

Students are learning how to use pictures to help them solve word problems and how to write a number sentence that corresponds with the problem posed.  Here are some examples:

Addition:
On Halloween, Marco got 8 peanut butter cups and 3 Hershey kisses.  How many pieces of candy did Marco get all together? 

First, students should write a number sentence to help them frame the problem:

                                  8 + 3 = 

Next, students should create a model of the problem using drawings, pictures, tallies, etc.

Now, students should be able to use their drawing to help them solve the problem and finish their number sentence.

                                  8 + 3 = 11

Subtraction:
9 birds were sitting on a tree branch.  Then 2 flew away.  How many birds were left sitting on the tree branch?
                                       9 - 2 = 

Once the model is drawn, use your picture to help you solve the problem!

                                       9 - 2 = 7

Missing Addend:
I planted 14 seeds.  6 of the seeds were apple seeds.  The rest were pumpkin seeds.  How many pumpkin seeds did I plant?

These are the hardest kind of word problems!  Many times, students want to add the two numbers they are given (14 and 6).  Remind your first grader see that 14 is the total (or sum).  We know one of the addends (6) but not the other.  The number sentence that correlates with the problem looks like this:


                               6 + ___ = 14

   

How many pumpkin seeds do you need to get 14 in all?  Finish the model to find out the answer!

                                     6 + 8 = 14

  

This week, we will introduce number stories with three addends.  Encourage your first graders to practice making up their own number stories and see if they can use a picture and a number sentence to solve them.  Have fun!