Amelia Law - Subtraction (Two-Digit)

Lesson Plans

PEPE Lesson Plan Format

(Alabama Professional Education Personnel Evaluation Program)

Written by: Amelia Law ablpol@hiwaay.net (Spring 2002)

Graphics, editing, and formatting by: Dr. Beth McCulloch Vinson

I. PREPARING

Materials:

Alabama Course of Study: Mathematics, page 22, number 6, children's literature: The Giving Tree, base tens with a picture of toys on them, dry erase board, and dry erase markers.

Objectives: The students will:

*identify two-digit numbers,

*learn the value of giving,

*solve two-digit subtraction problems, and

*experience giving.

Grade Level: second

II. ORIENTING:

Anticipatory Set: The teacher will read the book The Giving Tree. The teacher will talk about how the tree gave all he had to the boy that he loved. The teacher will express to the students the importance of giving and sharing. The teacher will tell the students we will use this lesson to learn how to subtract numbers with two-digits. The teacher will say, "Two-digit subtraction uses the same process as subtraction of numbers less than ten. She will then write the number “72” on the board and explain that the 7 is in the tens place and the 2 is in the ones place.

Purpose: The teacher will say, "The purpose of this lesson is to provide you the information necessary to subtract two-digit numbers. We will also define the term ‘two-digit number.’ This lesson is also going to help you understand the importance of giving and sharing."

Connection to previous learning/Build background knowledge: The teacher will say, "I know you can subtract numbers less than 10 and today we will subtract numbers greater than 10.”

III. PRESENTING

Teaching Procedures:

The teacher will say, "Two times a year my children go through their toys and select at least 12 toys they no longer play with. They give these toys to a charity that helps other children who need toys."

The teacher will say, "Lakin, my son, has about 38 toys. Sarah, my daughter, has about 29 toys."

The teacher will say, "Let's see how many toys Lakin has after he gives away 12.”

The teacher will remind the students that a two-digit number is when there is a number in the ones place and in the tens place.

The teacher will say we are going to learn how to subtract a two-digit number from another two-digit number.

The teacher will write the problem 38 - 12 = on the board.

The teacher will get out the base tens and the toy manipulatives. (Small, plastic party favors can be used as toy manipulatives.)

The teacher will take out 3 tens strips and 8 ones from her base tens.

The teacher will explain that you always start subtracting with the ones place.

The teacher will demonstrate the concept of 8 minus 2 is 6 using the base 10 ones.

The teacher will say, “Let’s look at the tens place. 3 groups of ten minus 1 group of ten equals 2 groups of ten.”

The teacher will say, “We have 2 groups of ten and 6 ones.”

The teacher will say, "Lakin has 26 toys left. He had 38 and gave 12 toys away. Now he has 26 toys left."

IV. PRACTICING AND SUMMARIZING

Review:

The teacher will ask a student to come to the board and write a two-digit number.

The teacher will ask, "What are two things the tree gave to the boy."

The teacher will ask, "Why is 11 a two-digit number?"

The teacher will ask the students to give examples of two-digit numbers.

The teacher will ask what students could do to help others.

Guided Practice:

The teacher will get out the toy manipulatives and give a set to each student.

The teacher will work the problem involving the number of toys Sarah will have left after she gives 12 away. The students will work the problem at their desks.

The teacher will give several sample problems and the students will work the problems using their base tens at their desks.

Independent Practice:

The teacher will ask everyone to get their manipulatives and form groups of four.

The teacher will instruct each group to create two-digit subtraction problems based on giving something to someone else. Each group must solve four problems.

Summarizing:

The teacher will say, "Today, we learned what a two-digit number is and how to use them in subtraction problems. We also learned how important it is to give and share with others. Tomorrow we are going to discuss a class project that involves giving to others.”

V. ASSESSMENT

The teacher will walk around the classroom and watch the students work independently. The teacher will look for correct answers. The teacher will listen to the students’ comments about giving to others. The teacher will grade the independent practice.

For enrichment, the students will get into groups of two and play Tic Tac Toe Math Subtraction. The players take turns answering math problems.

Subtraction Cards

Card #1 Card #1 Solution

Card #2 Card #2 Solution

For remediation, the student will use base tens to work single-digit problems. Students who have mastered the skill will team with students who need more practice.

See the two PowerPoint slide shows entitled,

“Subtraction” and “Subtraction with Regrouping” at:

http://www.athens.edu/pt3/vinson/subtraction.ppt

http://www.athens.edu/pt3/vinson/subtraction_r.ppt