In our unit, Equal Groups, situations are presented in context. The situation usually requires students to identify the number of groups and the number of items within each group.
There are 5 tricycles. Each tricycle has three wheels. How many wheels are there in all?
Or, the situation may read,
Tricycles have three wheels. There are 5 tricycles. How many wheels are there in all?
Number of Groups: 5
Number of Items in Each Group: 3
Students are taught to represent the problem with both an addition equation and a multiplication equation to illustrate the connection, and use a variable for the missing piece of information.
Addition equation: 3+3+3+3+3=w
Multiplication equation: 5x3=w (read 5 groups of 3)
Students generally begin solving the multiplication situations with their prior knowledge of repeated addition.
Repeated Addition: 3+3+3=9 and 3+3=6, so 9+6=15.
Then, some students move into skip counting if they can easily skip count by that number. If the situation allows counting skip counting by 2’s, 5’s, and 10’s, students will almost always start with this strategy. If however, the situation has them skip counting by 8’s, then we’ll teach students to use 10 as their anchor. Skip count by 10 and go back 2.
Skip Counting: 3,6,9,12,15.
One tool that we teach students to use to organize their thinking when skip counting is a ratio table. Ratio tables help students keep track of the number of groups as they skip count.