By: Mary Hovey                                                                                                                                                4/24/08

This activity is designed to introduce students to subtraction using the take away method. The objective of this lesson is that students will have a real example that relates to their world. Students will better understand the concept of the take away method of subtraction as it relates to the world in which they live in.

Learning Objectives

Students will be able to:

·         Relate real world situations to mathematics

·         Rely on tools that can be found within the real world to help them understand subtraction and mathematics

·         Better understand the symbols of subtraction, such as the minus (-) sign and the (=) sign

·         What it means to subtract whole numbers

·         Model the method of take away in subtraction

Materials:

·         Magnetic Board

·         Dry Erase Board

·         Dry Erase Markers (Black, Brown, Green, and Red)

·         Ten Magnetic Lizards

·         Copy of Tree-One per Student (See Attached)

·         Ten small toy lizards per students

·         One copy of Equation Page per Student (See Attached)

·         Pencil per Student

Instructional Plan:

1.      Explain the minus (-) sign to students: when we see this sign, we take away something, the answer will be less than the number that we will start with.

2.      It is important to first demonstrate the process that will be used.

3.      Draw examples of mathematical equation page (see Attached).

4.      Draw a picture of a tree on the magnetic white board.

5.      Pass out one copy of equation sheet, tree sheet, pencils and ten lizards per student.

6.      Ask students to wait for instructions before they do anything else.

7.      Place ten magnetic lizards on the tree that was drawn on the board.

8.      Ask students how many lizards that they see on the board.

9.      Tell students to place ten lizards on the tree that they have in front of them.

10.  Introduce the following rhyme: Ten little lizards sitting in a tree, one ran away and hid from me

11.  Remove one of the lizards from the tree, and ask the students to remove one of their lizards.

12.  Ask the students to help you find an equation for what happened with the lizards.

13.  Ask students how many lizards that there were in the tree…10

14.  Place 10 in the first box of the equation sample on the board

15.  Ask them to do the same on their paper.

16.  Ask the students how many lizards were taken away…1

17.  Place 1 in the next box on the equation example

18.  Have the students do the same

19.  Ask the students how many lizards are left in the tree…9

20.  Write this number in the third box of the equation sample.

21.  Ask the students to say the equation (10-1=9) with you.

22.  Repeat steps 8-20 until you reach zero.

Standards and Benchmarks:

Strand: Number and Operations; Standard: Students will understand numerical concepts and mathematical operations; K-4 Benchmark N.3: Compute fluently and make reasonable estimates.; Performance Standards: 1.N.3.3 Perform addition and subtraction with whole number combinations; 1.N.3.4 Use and explain estimation strategies to determine the reasonableness of answers involving addition and subtraction.

References:

Take Away. Retrieved April 19, 2008, from Illuminations Web site: http://illuminations.nctm.org/LessonDetail.aspx?id=L192