Teen numbers

The first instance of the Teen numbers 1 exercise is under the Early Math Math Mission. This exercise helps students to understand the naming scheme for the numbers between 10 and 20. It promotes a 'grouping by ten' way of looking at numbers in the teens.

Types of problems
There are three types of problems that show up in this exercise:
 * 1) Fill in the missing number: This problems shows between 10 and 20 objects and has the student determine how many more than ten are pictured. The answer has a student filling in the value to an equation.Teen-1.png
 * 2) Fill in how many more to get: This problem has a picture of ten objects and asks the student to decide how many more they would need to get a certain number. It also has the student fill in a blank to complete an equation.Teen-2.png
 * 3) Select the picture with right number: This problem asks a student to select the collection that has a certain number of objects. They are also expected to fill in a blank to complete an equation.Teen-3.png

Strategies
Although some of these problems are free response, they still can be done very quickly which makes this exercise easy to earn speed and accuracy badges.


 * 1) On the second problem type, the number beyond ten and the answer to fill in the equation are the same number, illustrating the relationship between the ones digit and the number beyond ten. Once one is determined, the other can be immediately answered.
 * 2) On the third problem type, the correct picture always has a group of ten and a group with the number beyond ten. This makes it easy to tell which picture is the correct one by comparing the size of the "beyond 10" row to the row that has ten.