Addition and Subtraction within 20
Using Bar Models
In this video, we will learn how to
use bar models to represent addition and subtraction problems. We can use a bar model to help us
solve an addition problem. Let’s try an example.
The question asks us to find
the missing number: 11 plus seven equals the missing number.
The bar model represents an
addition problem: 11 plus seven. There are 11 blue cubes in the
model, and there are seven orange cubes. If we add the blue bricks and
the orange bricks together, we can count the total number of bricks. We can start counting at 11 and
count forward seven more: 11, 12, 13, 14, 15, 16, 17, 18. 11 and seven more makes 18 in
total. 11 plus seven is 18.
Now let’s look at an example of a
Find the missing number to make
the equation correct: 13 take away six equals the missing number. The bar model shows us that
there are 13 bricks at the start. And we need to take away
six. This will give us the missing
number. So if we take away six, how
many will be left?
We need to count the number of
blue bricks: one, two, three, four, five, six, seven. There were 13 bricks at the
start. We took away six. Seven were left.
In this video, we’ve learned how to
use bar models to help us solve addition and subtraction problems.