### Joe CrawleyCitrus County Schools

#### Description

This lesson helps to lay a foundation for solving addition and subtraction word problems. It will be the basis for future lessons on addition, subtraction, multiplication, and division. The students will explore the reasons for adding or subtracting.

#### Objectives

The student knows the effects of the four basic operations on whole numbers, fractions, mixed numbers, and decimals.

#### Materials

-20 marbles per group in at least 3 colors
-1 sheet of paper per group
-1 pencil per group

#### Preparations

1. Gather marbles.
2. Hand out paper.
3. Gather materials for activity.
4. Run off a copy of the associated file for each student.

#### Procedures

This plan only includes the subtraction and addition portion of the Benchmark.

We add when the problem wants to know a total ( stated or implied) and the numbers are different.

Stated Example: Jim weighs 122 pounds, Harry weighs 180 pounds, and Sally weighs 105 pounds. What is their total weight?

Implied Example: Joy has \$25 in her purse and \$10 in her pocket. How much money does Joy have?

2. SUBTRACTION
We subtract when the problem takes away, is a have and need, compares and asks or implies what is the rest.

A TAKE AWAY problem states that there are only so many of an item and a certain quantity is removed or taken away. Example: John has \$25.30 and spends \$3.75. How much money does John have left? (Answer: \$3.75 was taken away.)

A HAVE AND NEED problem indicates that a certain amount is available, but an additional amount is needed. Example: The recipe calls for 2.5 cups of sugar and Joe has 1.25 cups. How much more sugar does Joe need?

A COMPARE problem asks for a comparison of numbers. How much more or how much less. Example: Harry weighs 130 pounds and Jack weighs 198 pounds. How much more does Jack weigh than Harry?

WHAT IS THE REST problem provides a total and then gives a portion of that total and then asks what the other portion is (the rest). Example: There are fifty-five balls in the bag. Twenty are red balls, and the rest are blue balls. How many blue balls are in the bag?

3. Divide students into groups of two students. Each student will create his or her own subtraction and addition word problems. Have them switch with their partner to solve. They must also explain what type of subtraction or addition problem it is.

4. Provide a practice sheet of subtraction and addition word problems to the students. Have the students work the word problems and explain why they added or subtracted.

5. Students are divided into pairs and use their colored marbles to design different types of addition and subtraction word problems.

EXAMPLE ADDITION: Student will place 7 marbles and then 9 marbles together and ask how many marbles in total.

EXAMPLE TAKE AWAY: Student will take 15 marbles away from their stack of 25 marbles, and then determine how many are left.

EXAMPLE COMPARE: Each student in the group will have a different number of marbles. They will determine how many more marbles one has than the other.

EXAMPLE HAVE AND NEED: A student's project calls for 35 marbles. Together they have 25 marbles. They will determine how many more marbles they need.

EXAMPLE WHAT IS THE REST: The students have 10 blue marbes. They have a total of 25 marbles. The rest of the marbles are red. Have them determine how many are red.

6. Assess students' problems. (See Assessment.)

#### Assessments

Students will solve a series of real-world addition and subtraction problems. They will state if the problem is addition or subtraction and why. Students will be able to show that they understand when to add or subtract by answering six of the seven problems correctly from the extension folder and by teacher observation.

A Review of Place Values

A Review of Subtracting Fractions