Hi. I'm John SanGiovanni, Coordinator of
Elementary Mathematics.
And this is Math in Minutes.
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In this segment, we are going
to look at addition on a number line.
Number lines help us represent and
understand the mathematics.
In this example, we will use an open 
number line to show the addition.
Let's look at the problem 24 plus 32.
Our students could make jumps of one,
but instead we're going to focus 
on more efficient strategies.
They could begin with 24.
And add on by tens.
10.
20.
30.
After adding the tens,
they can then show jumps of ones.
So they've shown 24 plus 32
by adding 10,
20,
30,
31. 32.
24 plus 32 is 56.
In time,
our students
can add these numbers 
by adding groups of 10.
For example, 24
and 30
and then two more.
In this case, 24 plus 32 is 56.
We can see how these 
two number lines are connected,
but how this one in red is more efficient.
As we know, we can begin 
with either add in
when finding the sum of
24 and 32.
Students may begin with 32
and add a group of 20,
and then a group of
four.
Doing so, the sum is unchanged.
32 plus 24 is 56.
This is also understanding,
or exhibiting understanding,
of a commutative property.
Adding on a number line also helps us 
make sense of
addition with regrouping.
Let's take a
look at another problem.
Let's examine 38 plus 14.
In 38 plus 14.
We can start with 38,
make a jump of 10,
and then add on four more.
So 38 plus 14 is
48,
49, 50, 51, 52.
38 plus 14 is 52.
In time, our students can think about 
38 plus 14,
as 38 plus 10,
plus 2 more,
plus 2 more.
In this case, 38 plus 10,
12,
14,
is 52.
Using a number line helps us see 
different ways to add numbers.
In time,
this helps our students develop 
efficient strategies for addition.
See you next time 
on Math in Minutes.
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