Adding and Subtracting

Adding and Subtracting

What is addition?

• Addition, or “adding,” is putting things together.

• You write addition with the “+” sign. We call it a “plus” sign.

Can you say…

• 1 + 1 : one plus one• 2+1 : • two plus one• 4 + 2: • four plus two

Addition ProblemLet’s think about it…

• Josh has 2 footballs and his dad gives him 1 more for his birthday. How many footballs does Josh have now?

•

Let’s think about it…

• What is this problem asking you to do?

-Josh has 2 footballs, and now he is getting 2 more from his dad. This means we are putting things together, or adding.

Are we gaining?

If you are putting things together, will you end up with more or less?

• MORE!!!!

Write it out!

• We started with 2, and now we have 2 more. So we write it as: 2 + 2 = ?

How to solve it

• You can use either a number line or draw pictures.

Use a number line

• We can use a number line to help us add:

We started at 2 and ended with 4. Thus, Josh now has 4 footballs.

How many do you see?

4

How to write it…

• Josh started with 2 footballs, his dad gives him 2 more.

• So we write it as 2 + 2 = 4

ADDITION as “ Sum”

• What is the sum of 3 and 1?

Let’s Think!

• Sum means total, total means the ending amount. In other words, “what is the sum” simply means “what is the total amount?”

What is the sum of 3 and 1?

The sum of 3 and 1 may be written as 3 + 13 + 1 = ?

3 + 1 = 4

Subtraction

• Subtraction: Taking away from a number.• Subtraction is written with the“ –” sign. We

call this sign “subtraction sign, or the minus sign.”

• The word “difference” also represents the idea of subtraction.

Can we say?

• 1 – 1 : one minus 1• 2 – 1 : two minus 1• 4 – 2 : four minus 2

We have a problem…

• Lily has 4 pieces of chocolate. Her mother asked her to give 2 pieces to her brother. How many does Lily have left?

Let’s think!

• When you have 4 pieces of candies, and you give away 2 of them, will you end up with more or less?

•Less!

This means that…

We start with 4 pieces of candies and give away 2.

In other words, we are taking away 2 pieces of candies.

This may be written as: 4 – 2 = ?

4 - 2 =?

• Use the number line:

We started at 4, we took away 2 and ended up at the number 2. Thus, 4 – 2, or 4 take away 2 is equal to 2.

Draw it out!

We started with 4, and we took a away 2. We now have 2 left.

In other words…

• Lily started with 4 pieces of candies, and she gave away 2 to her brother. We write this as

• 4 – 2 = 2.

What is “difference?”

• Tom is 7 years old. His brother is 3 years old. What are the difference in their age?

Let’s think about it…

• What does difference mean? The difference means the gap or distance between 2 numbers.

• If Tom is 7 years old and his brother is 3. The difference in their age means how much older is Tom than his brother, or how many years apart they are.

Set up the equation

• The difference in their age may be written as :• 7 – 3 = ?

7 – 3 =?

• What is 7 take away 3, or 7 – 3?

• 4!• So Tom and his brother are 4 years apart.

Let’s Review!

Quiz Time!

Problem #1

• Luke ate 2 drumsticks for lunch. He got hungry later in the day and ate 3 more. How many drumsticks did Luke ate in today?

• A. 4• B. 5• C. 3• D. 7

•Correct!

Problem #2

• Ann went to pick flowers for her mother. We picked 5 but when she got home she only had 2. How many flowers did she lose on the way home?

• A. 1• B. 2• C. 3• D. 4

•Fantastic!

TEKSTEKS: §111.3. Grade 1, Adopted 2012.§111.3. Grade 1, Adopted 2012.(4) The primary focal areas in Grade 1 are understanding and applying place value, solving problems involving addition and subtraction. (A) Students use relationships within the numeration system to understand the sequential order of the counting numbers and their relative magnitude.(B) Students extend their use of addition and subtraction beyond the actions of joining and separating to include comparing and combining. Students use properties of operations and the relationship between addition and subtraction to solve problems. By comparing a variety of solution strategies, students use efficient, accurate, and generalizable methods to perform operations.

Credits

• http://www.math.com/school/subject1/lessons/S1U1L11GL.html• http://www.math.com/school/subject1/lessons/S1U1L11DP.html• http://www.google.com/search?client=safari&rls=en&q=synonyms+of+

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• http://seattlemet.dev.interfacecms.com/eat-and-drink/articles/0309-svc-chocolate/

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