Join+Change+Unknown

__**Join Change Unknown**__

Connie has 5 marbles. How many more marbles does she need to have 13 altogether?

Using the **Direct Modeling Strategy**: Using Unifix cubes, the student counts out a group of five cubes and then joins to the five cubes until they reach 13 cubes, noticing that they had to add 8 additional cubes.

5 + ? = 13

Start with the number 5 in your head, then count on to 13 (eight places).
 * Counting Strategy:**

5 * * * * * * * * (13) 5+ 8 = 13

Start with the number 13 in your head, then count down to 5 (eight places).

13 * * * * * * * * (5) 13 - 8 = 5


 * Fact Strategy:**

Problem: 5 + __ = 13.

Although we do not know what to add to 5 to equal 13, we do know that 5 +5 = 10 and that 10 + 3 = 13. In order to arrive at the number 13 above, we added 5 and 3 to get 8, so 5 + 3 = 8, therefore, 5 + 8 = 13.

Kindergarten Class Example