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Tips and Activities
Teaching
Addition and Subtraction:
There are many
ways to teach addition and subtraction. All teachers have their own ways
of doing it but here are some ideas, tips, and activities that can help
you.
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Manipulatives:
The most important thing to remember when introducing or practicing
the concepts of addition and subtraction is to use manipulatives. By
using manipulatives, students are able to master basic facts. Many
items can be used as manipulatives, ranging from food to school
supplies.
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Fact
Family Homes: Fact
families can be a difficult concept for students to understand, so
here is an activity to help them master the concept. First, I
teach students that in a fact family, there are four number sentences
which use only the three numbers. For example: 2,4,6
make up a fact family
which looks something like this:
2+4=6
6-4=2
4+2=6
6-2=4
The students learn
that the same three numbers are used throughout the fact family and
that they just change spots when they go into another number sentence.
After this lesson (which takes between 1-2 days, depending on
age/grade level), the students then create homes for the fact
families. Here is an illustration of what their fact family homes will
look like:
You
can use milk cartons covered with construction paper to create 4 fact
family homes (1 on each side). Or, students can use large sheets of
construction paper to create larger homes that can be assembled to create
a bulletin board. See Learning
Centers below to see an extension activity to this one. Click the
picture to download a practice worksheet on fact families.
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Two Digit
Addition/Subtraction (No regrouping): To introduce this concept, you
will need to review place value, particularly the tens and ones
columns. Here is how I teach them to add/subtract two digit
numbers. First, I show them the problem on the board--
45
+23
Then I show the students that the problem has two columns, a ones
column and a ten columns. This is where I place my pre-made
construction paper columns on the board and write the problem on the
columns--
This helps
illustrate to students to start adding/subtracting the green column
(green=start) and then add/subtract the red column (red=stop).
When doing three digit addition/subtraction, the ones column is green,
tens column is yellow, and the hundreds column is red. In this
way, you are utilizing traffic light signals and colors which they
should already be familiar with. Once they've become used to
seeing the construction paper columns, they are able to name the
columns without any problem.
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Two Digit
Addition with Regrouping: Addition with regrouping requires the
students to use manipulatives to demonstrate how they move
"ten" ones over to the tens column. Here is an example
of how I begin teaching addition with regrouping. Using the
construction columns (see above), students are asked to show the
number 12 using only ones manipulatives and placing a ten manipulative
in the tens column. This is when the students are taught that
there can be no more than 9 ones in the ones column. Through
some direct guidance, students realize they need to move ten ones over
into the tens column as illustrated below--
As
we practice this more I show them how this concept is incorporated into
two-digit addition problems. I have found this lesson to be the best when
it comes to introducing regrouping to the children. I have tried teaching
regrouping without using manipulatives or showing the concept of
"shifting ten over to the tens column" as we call it......and
the majority of the students had a hard time learning this concept.
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Two-Digit
Subtraction with Regrouping:
Here is a cute idea to teach kids when to "borrow" in a
subtraction problem. The name of the rule is the "BBB
Rule". The BBB rules states "When the BIG number is
on the BOTTOM, then you BORROW."
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Finger
Counting: Many
teachers are against students using their fingers to count. But
when students are doing the math section of a standardized test with a
time limit, I want them to utilize their time efficiently.
Although I do enforce mental math with the children, there are times
when they will need to quickly add/subtract. These are some
tricks that I've taught the students:
1. Adding: When adding 6 + 4, students must ask themselves "Open
or closed?" With addition it is open.
They open their hands and raise up four fingers (the smallest number).
The palm of their hand says "6" and then they continue
counting on the four fingers to get the sum.
2. Subtracting: When subtracting 15 - 8, students must ask themselves
"Open or closed?" With subtraction it is closed. The put
their hand in a fist and their palms will say the smallest number
("8"). They will count up to the higher number, which
is 15. When they reach 15, they count how many fingers are standing to
get their answer.
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