Unit 2, Lesson 1

Unit 2, Lesson 1 Addition Facts Strategies

Unit 2, Lesson 1 Unit 2, Lesson 1 Unit 2, Lesson 1 Unit 2, Lesson 1

Addition Facts StrategiesAddition Facts Strategies


Goals• Commutative and associative

properties of addition• Practice addition facts strategies


What We Will Learn Today

• We are going to learn that we can add numbers in any order and still get the same answer.

• That can group numbers together any way we want when we add.

• It is easier to add numbers when you make groups of ten.


Using a Ten• You will work in pairs.

• Each pair will have 40 connecting cubes.

• Materials getters, please get a bag of cubes and give 4 trains of 10 to each pair in your group. Please make sure that they have four different colors.


Using a Ten• You have enough cubes for you to

do some of these activities on your own.

• Some of the activities will require that you work together with your cubes.


Using a Ten• I want each student to take two

different colors of connecting cubes.

• Build one train with 7 cubes of one color.

• Building another train with 8 cubes of another color.


Using a Ten• What can you do with your cubes to

make a train of ten?• Yes, move two cubes from the train of

seven cubes to the train of eight cubes.

• Or, move three cubes from the train of eight cubes to the train of seven cubes.


Using a Ten• You now have a train of 10 cubes and

a train of 5 cubes. What is the sum?

• 15

• Why is this problem (10 + 5) easier to solve than the first one (7 + 8)?


Vocabulary• Addend – a number that is

added to another

• Sum – the answer to an addition sentence


Teaching the Activity• Do the following problems by

making a train of one color for the first addend and a train of another color for the second addend.

• 6 + 7• Why is 10 + 3 easier to solve than 6 + 7?


Teaching the Activity• 8 + 8

• Why is 10 + 6 easier to solve than 8 + 8?


Teaching the Activity• 8 + 9

• Why is 10 + 7 easier to add than 8 + 9?


Switch It!• These next problems you will have

to do in pairs.• Solve 14 + 7 + 6 with connecting

cubes. Use a different color for each addend.

• Group the cubes in as many tens as possible.


Switch It!• What can you do with the train of

14?• What can you group together to

make a ten?• What is your answer?


Switch It!• Let’s share your solutions.


Challenge• Try to add 14 + 7 + 6 using

mental arithmetic. • See if you can rearrange any of

the numbers to make groups of ten.

• How did you solve this without paper, pencil or cubes?


More Problems• Do these problems first with

mental addition. Try to find groups of 10. You may also use doubles.

• Then use your cubes.• 8 + 7 + 12• 6 + 8 + 14• 11 + 3 + 9



Vocabulary• Partition – To divide into parts.

• Ex: 7 can be divided into 5 and 2


Breaking Addends into Parts

• Sometimes addends can be easily grouped into tens.

• Sometimes this isn’t easy to see.

• Try partitioning addends before finding groups of ten.



• Example: 7 + 5 + 2• The second addend, 5, can be

rewritten as 3 + 2.• 7 + 3 + 2 + 2• What two numbers can you group

together to make 10?• What is the sum?



• Work with your partners to solve the following problems.

• Use your math notebook to write the number sentence and then show how you partitioned the number.


Breaking Addends into Part

•6 + 8 + 3•9 + 7 + 2•4 + 9 + 3•Let’s compare your solutions.


My Calculator is Broken• We are going to imagine that

some of the keys on the calculator are broken.

• That means that you cannot use those keys.

• .


My Calculator is Broken• First, let’s imagine the five is

broken.• What keys would you press to do

the problem 9 + 5 + 2?• Share your solutions.


My Calculator is Broken• Do these additional problems

without using the 5 key.• 8 + 5• Share your solutions• 5 + 7 + 6• Share your solutions


My Calculator is Broken• 15 + 6 + 3• Share your solutions• 9 + 25• Share your solutions


What We have Learned• We learned that we can add

numbers in any order and still get the same answer.

• We can group numbers together any way we want when we add.

• It is easier to add numbers when you make groups of ten.

Documents

Unit 2, Lesson 1