Mastering Addition Within 20: Concepts and Properties
Grade 1 Mathematics Term 1 Week 8. Designed by Expert Educators and Validated for Curriculum Alignment.
SESSION 1 • OBJECTIVE
SESSION 1 LEARNING OBJECTIVES
Today we will learn to describe addition as putting together and counting up using groups of objects and number lines.
SESSION 1 • REVIEW
REVIEW: COUNTING TO 20
Let us practice counting from 1 to 20 together. Look at the number symbols on the screen and identify them as we go.
SESSION 1 • MOTIVATION
THE GROUPING GAME
Look at these two groups of students. We have three friends on the left and four friends on the right. What happens if they walk toward each other?
SESSION 1 • PRESENTATION
WHAT IS ADDITION?
Addition is the process of joining groups to find a total. We use words like putting together to explain how we combine things.
SESSION 1 • DISCUSSION
THE STORY OF THE TWO GROUPS
Once there were three blue birds sitting on a fence. Soon, four red birds flew down to join them. They all sat together in one big row.
SESSION 1 • DISCUSSION
PUTTING TOGETHER EXPLAINED
When the birds sat together, we did not take any away. We combined the first group with the second group. This is called finding the sum.
SESSION 1 • DISCUSSION
THE NUMBER LINE SECRET
There is another way to add. It is called counting up. Imagine a little frog sitting on a number line at the number eight.
SESSION 1 • DISCUSSION
THE FROG'S BIG JUMP
If the problem is 8 plus 5, the frog starts at 8. He hops forward 5 times. Each hop takes him to a bigger number.
SESSION 1 • DISCUSSION
COUNTING ALOUD
Let us count with the frog. He starts at 8. Hop 1 is 9. Hop 2 is 10. Hop 3 is 11. Hop 4 is 12. Hop 5 is 13.
SESSION 1 • DISCUSSION
WHY START WITH THE LARGER NUMBER?
Counting up is faster if you start from the larger number. It saves time and helps you reach the answer more quickly.
SESSION 1 • ACTIVITY
STONE COUNTING ACTIVITY
Take your 10 stones. Put 6 on the left. Put 4 on the right. Move them into one pile and count how many you have in total.
SESSION 1 • GENERALIZATION
WHAT WE LEARNED TODAY
We learned two ways to think about addition. We can put groups together or we can count up from a number on a line.
SESSION 1 • ASSESSMENT
QUESTION 1
When we join two groups of objects, what are we doing?
A. Subtracting
B. Adding
C. Dividing
D. Subtracting
SESSION 1 • ASSESSMENT
QUESTION 2
To solve 7 + 3 by counting up, what is the first number you say after 7?
A. 7
B. 8
C. 10
D. 6
SESSION 1 • ASSESSMENT
QUESTION 3
What is the sum of 10 and 4?
A. 6
B. 12
C. 14
D. 20
SESSION 1 • ASSESSMENT
QUESTION 4
If you have 15 marbles and put them together with 5 more, how many do you have?
A. 10
B. 15
C. 20
D. 25
SESSION 1 • ASSESSMENT
QUESTION 5
Which word describes the answer in addition?
A. Difference
B. Product
C. Sum
D. Minus
SESSION 2 • OBJECTIVE
SESSION 2 LEARNING OBJECTIVES
Today we will illustrate addition of numbers with sums up to 20 using concrete manipulatives and pictorial models.
SESSION 2 • REVIEW
REVIEW: PUTTING TOGETHER
Remember yesterday? We learned that addition means joining groups. Let us quickly add 5 and 5 by putting our fingers together.
SESSION 2 • MOTIVATION
THE FRUIT BASKET MYSTERY
Here is a basket with 12 plastic fruits. If I add 6 more fruits, how can we show this without using real fruit?
SESSION 2 • PRESENTATION
CONCRETE AND PICTORIAL MODELS
We can use real objects like sticks to show addition. We can also use drawings like circles or squares to see the numbers.
SESSION 2 • DISCUSSION
THE POWER OF CONCRETE OBJECTS
Concrete objects are things you can touch. When we use popsicle sticks, we can feel the amount of the numbers in our hands.
SESSION 2 • DISCUSSION
BUILDING A PILE
Imagine one student makes a pile of 9 sticks. Another student makes a pile of 7 sticks. When they join them, they count 16.
SESSION 2 • DISCUSSION
MOVING TO DRAWINGS
Sometimes we do not have sticks. We can draw pictorial models instead. We can draw 5 squares and then 8 more squares.
SESSION 2 • DISCUSSION
GROUPING BY TENS
To make counting easier in our drawings, we can group ten objects together. This helps us see that 10 and 3 make 13.
SESSION 2 • DISCUSSION
VISUALIZING THE SUM
Pictorial models help us visualize numbers. Even without real objects, we can see how large a number is by looking at the shapes.
SESSION 2 • DISCUSSION
USING ADDITION MATS
An addition mat has two sides. We can put buttons on one side and draw circles on the other side to find the total.
SESSION 2 • ACTIVITY
DRAWING YOUR SUMS
On your slates, draw 11 circles. Now draw 4 more. Count all the circles you drew to find the total sum.
SESSION 2 • GENERALIZATION
OBJECTS AND PICTURES
Whether we use sticks or drawings, the sum stays the same if the parts are the same. Models help us understand math better.
SESSION 2 • ASSESSMENT
QUESTION 1
Which picture shows 3 + 2?
A. 3 balls and 2 balls
B. 5 balls
C. 3 balls cross out 2
D. 1 ball
SESSION 2 • ASSESSMENT
QUESTION 2
If you draw 8 stars and then 8 more, what is the total?
A. 14
B. 15
C. 16
D. 18
SESSION 2 • ASSESSMENT
QUESTION 3
Which model represents 'counting up' from 11?
A. A number line with a jump from 11 to 14
B. Two separate circles
C. An empty box
D. A minus sign
SESSION 2 • ASSESSMENT
QUESTION 4
What is 12 + 5 using a model?
A. 7
B. 15
C. 17
D. 19
SESSION 2 • ASSESSMENT
QUESTION 5
How many are 6 squares and 6 squares together?
A. 10
B. 11
C. 12
D. 13
SESSION 3 • OBJECTIVE
SESSION 3 LEARNING OBJECTIVES
Today we will apply the Identity Property of addition to show that the sum of zero and any number is the number itself.
SESSION 3 • REVIEW
REVIEW: USING MODELS
We used sticks and drawings yesterday. Today, we will look at what happens when one of those groups has nothing in it.
SESSION 3 • MOTIVATION
THE MAGIC ZERO TRICK
I have 5 candies in this box. I am adding zero candies from my empty hand. How many candies are in the box now?
SESSION 3 • PRESENTATION
THE IDENTITY PROPERTY
Zero means none or nothing. When we add zero to a number, the number does not change. It keeps its identity.
SESSION 3 • DISCUSSION
THE STORY OF MAGIC ZERO
Zero is like a ghost. He walks into a room where there are 7 people. He joins them, but there are still only 7 people there.
SESSION 3 • DISCUSSION
ZERO IN THE REAL WORLD
Think about your lunchbox. If you have 2 sandwiches and your mom adds zero more, you still have exactly 2 sandwiches to eat.
SESSION 3 • DISCUSSION
ADDING ZERO TO LARGE NUMBERS
It does not matter how big the number is. If we have 19 and add 0, the sum is 19. The rule always stays the same.
SESSION 3 • DISCUSSION
THE HULA HOOP EXPERIMENT
Imagine two hula hoops. One hoop has 8 balls. The other hoop is empty. If we combine them, we still count only 8 balls.
SESSION 3 • DISCUSSION
ZERO AS THE FIRST ADDEND
What if zero comes first? 0 plus 13 is still 13. Zero does not have the power to change any number it is added to.
SESSION 3 • DISCUSSION
THE IDENTITY CHANT
Let us say it together: Any number plus zero is the same number! 100 plus zero is 100. 1 million plus zero is 1 million.
SESSION 3 • ACTIVITY
ZERO FLASHCARD DRILL
When you see the flashcard, shout the sum! 15 + 0? 0 + 6? 18 + 0? Remember the identity rule for every card.
SESSION 3 • GENERALIZATION
THE ZERO RULE
The sum of zero and any number is equal to that number. This is a special rule called the Identity Property.
SESSION 3 • ASSESSMENT
QUESTION 1
What is 9 + 0?
A. 0
B. 1
C. 9
D. 10
SESSION 3 • ASSESSMENT
QUESTION 2
If a basket has 0 mangoes and you add 18, how many are there?
A. 0
B. 18
C. 19
D. 8
SESSION 3 • ASSESSMENT
QUESTION 3
Which number sentence shows the Zero Property?
A. 1 + 1 = 2
B. 5 + 0 = 5
C. 2 + 3 = 3 + 2
D. 10 - 0 = 10
SESSION 3 • ASSESSMENT
QUESTION 4
What happens when you add zero to 20?
A. It becomes 0
B. It becomes 21
C. It stays 20
D. It becomes 10
SESSION 3 • ASSESSMENT
QUESTION 5
0 + 13 = ?
A. 0
B. 1
C. 13
D. 31
SESSION 4 • OBJECTIVE
SESSION 4 LEARNING OBJECTIVES
Today we will apply the Commutative Property of addition to show that changing the order of addends does not change the sum.
SESSION 4 • REVIEW
REVIEW: THE ZERO RULE
Yesterday we learned that zero does not change the sum. Today we will see what happens when we switch numbers around.
SESSION 4 • MOTIVATION
SWITCHING PLACES
Anna has 5 blue blocks. Ben has 3 red blocks. Total is 8. If they switch blocks, does the total change?
SESSION 4 • PRESENTATION
THE COMMUTATIVE PROPERTY
This is also called the Order Property. It means you can swap the numbers you are adding and the sum will be the same.
SESSION 4 • DISCUSSION
THE FRIENDSHIP BRIDGE
Imagine two numbers, 6 and 4, meeting on a bridge. Whether 6 comes first or 4 comes first, they still make 10 together.
SESSION 4 • DISCUSSION
THE BALANCE SCALE
Think of a balance scale. On one side we have 6 + 4. On the other side we have 4 + 6. The scale stays perfectly level.
SESSION 4 • DISCUSSION
TWO-COLORED COUNTERS
If you have a row of 7 red counters and 2 yellow counters, it is 9. Flip them to 2 yellow and 7 red. It is still 9.
SESSION 4 • DISCUSSION
FINDING THE MISSING FRIEND
If we know that 10 + 2 = 12, then we also know that 2 + 10 must be 12. We don't even have to count again!
SESSION 4 • DISCUSSION
ORDER DOESN'T MATTER
In addition, the numbers are like friends in a line. It doesn't matter who stands in front; the whole group is still the same.
SESSION 4 • DISCUSSION
PATTERN RECOGNITION
Look at these: 5 + 8 = 8 + 5. 11 + 4 = 4 + 11. Can you see how the numbers just swap their spots?
SESSION 4 • ACTIVITY
ORDER PROPERTY PUZZLES
Fill in the blanks: 10 + 2 = 2 + __. 5 + 8 = 8 + __. 11 + 4 = __ + 11. Use your counters to check.
SESSION 4 • GENERALIZATION
THE RULE OF ORDER
Changing the order of the addends does not change the sum. This is the Commutative Property of Addition.
SESSION 4 • ASSESSMENT
QUESTION 1
If 5 + 4 = 9, then 4 + 5 = ?
A. 1
B. 5
C. 4
D. 9
SESSION 4 • ASSESSMENT
QUESTION 2
Which shows the order property?
A. 2 + 0 = 2
B. 8 + 3 = 3 + 8
C. 10 + 1 = 11
D. 5 - 2 = 3
SESSION 4 • ASSESSMENT
QUESTION 3
Complete the sentence: 12 + 6 = 6 + __.
A. 6
B. 12
C. 18
D. 0
SESSION 4 • ASSESSMENT
QUESTION 4
Does changing the order of numbers change the sum?
A. Yes
B. No
C. Sometimes
D. Only for zero
SESSION 4 • ASSESSMENT
QUESTION 5
7 + 11 is the same as:
A. 11 + 7
B. 11 - 7
C. 7 + 0
D. 11 + 11
SESSION 5 • OBJECTIVE
SESSION 5 LEARNING OBJECTIVES
Today we will solve basic addition problems and word problems by integrating models, counting strategies, and properties.
SESSION 5 • REVIEW
REVIEW OF THE WEEK
We have learned putting together, counting up, pictorial models, the zero property, and the order property. You are math experts!
SESSION 5 • MOTIVATION
MATH DETECTIVE DAY
Today you are all Math Detectives. You will use your skills to solve mysteries and find the missing sums around the room.
SESSION 5 • PRESENTATION
SOLVING WORD PROBLEMS
Word problems are like stories with numbers. We have to read carefully to find out what the problem is asking us to do.
SESSION 5 • DISCUSSION
THE CASE OF MARIA'S STICKERS
Maria has 12 stickers. Her friend gives her 0 more. How many does she have? We use the Identity Property to solve this.
SESSION 5 • DISCUSSION
THE CASE OF JOSE AND PEDRO
Jose adds 5 + 9. Pedro adds 9 + 5. Who has more? We use the Commutative Property to know they both have the same.
SESSION 5 • DISCUSSION
USING THE BEST STRATEGY
Detectives choose the best tool. For 18 + 2, we might count up. For 10 + 7, we might use a pictorial model.
SESSION 5 • DISCUSSION
CHECKING YOUR WORK
Always check your answer. You can use your fingers or sticks to make sure your sum is correct before moving to the next case.
SESSION 5 • ACTIVITY
THE SUM IS 15 GAME
Stand up if the model I show represents a sum of 15. Look at 10 + 5, 0 + 15, and 5 + 10 carefully!
SESSION 5 • GENERALIZATION
MASTERING ADDITION
You now know how to add numbers up to 20 using many different tools and rules. Addition is everywhere in our lives!
SESSION 5 • ASSESSMENT
SUMMATIVE QUESTION 1
Maria has 14 pesos and her dad gives her 0 pesos. How much does she have?
A. 0
B. 14
C. 15
D. 28
SESSION 5 • ASSESSMENT
SUMMATIVE QUESTION 2
Start at 13 and count up 4. What is the number?
A. 16
B. 17
C. 18
D. 19
SESSION 5 • ASSESSMENT
SUMMATIVE QUESTION 3
Which property is 15 + 2 = 2 + 15?
A. Zero Property
B. Order Property
C. Counting Up
D. Putting Together
SESSION 5 • ASSESSMENT
SUMMATIVE QUESTION 4
What is the sum of 9 + 9?
A. 0
B. 18
C. 19
D. 20
SESSION 5 • ASSESSMENT
SUMMATIVE QUESTION 5
A pictorial model shows 10 dots and 7 dots. What is the sum?
A. 10
B. 7
C. 17
D. 3