Objectives - Students will be able:

1)    Subtract negative numbers.

2)    Model the meaning of subtraction with positive and negative integers using charged particles.

3)    State the rule for subtraction of signed numbers.

4)    Solve a word problem of appropriate difficulty using signed numbers and explaining the reasoning.

Materials Needed:

Whiteboards, dry erase markers, tile spacers, and scissors

Activities:

1)    Brainstorm List of opposites to build schema about integers.

2)    Connect to what the students already know. What is addition, subtraction?

3)    Teacher models how + and – equal 0, a neutral field of zeros.

4)    Students have manipulatives on desks and teacher leads them to explore 3 – 2.

5)    Teacher changes the algorithm to 3- (-2), challenging the students to finish the model.

6)    Students draw models on whiteboards, and displaying so teacher can check for understanding.

7)    Students model 3 –(-2)  and 3+2 side by side on whiteboards comparing solutions and realizing subtracting is the same as adding the opposite.

8)    Students solve word problem using this model to explain their reasoning.

   Teaching Strategies

1)    Tile spacers are concrete models that tap into kinesthetic intelligence.

2)    Whiteboards permit checking for understanding.

3)    Drawing charges are a scaffold that can be used at anytime to refresh understanding

4)    Brainstorming builds schema about the use of integers in subtraction in word problems

Assessment/Evaluation

1)    The student can draw a model of a subtraction model using charges.

2)    The student can solve word problems and explain their reasoning

. The teacher will administer a pre and posttest that will require a student to solve and explain their reasoning in word problems that involve opposites.

3)    The problems will be given in a series of leveled difficulties providing differentiated assessment. The initial question will be so easy all could do it mentally. The difficulty progresses to challenge the gifted student.