What is in the Box? Solving a Math Problem

This week in Math we have been solving problems using what we know about numbers.  This is the problem we were solving today:

     There are 12 stickers in a box.
     Some are red and some are yellow.
     There are 2 more yellow stickers that red stickers.
     How many yellow stickers are there?

We began by thinking of all the ways that we could show 12 using addition sentences (0+12, 1+11, 2+10, 3+9, etc.).  
Students then used two-sided counters to try the Guess and Check strategy. They spilled 12 counters and compared how many red and yellow appeared. Then they drew a picture and checked to see if it matched the clues that were in the problem. If it didn't, they tried again.  After a few guesses (some students were very lucky and got it on the first try!) the correct answer was reached:  There were 7 yellow stickers in the box!

This student is comparing the red and yellow "stickers" to see if there are two more yellow than red.  This guess was not correct, so he had to try again.