LESSON PLAN OF DISTRIBUTIVE LAW

LESSON PLANNING OF DISTRIBUTIVE LAW

Subject Mathematics

Grade 5^th

Students` Learning Outcomes

Information for Teachers

Distributive law collects multiplication and addition subtraction operations;
o Distributive Law w.r.t addition x(b + c) = a x b + a x c
o Distributive law w.r.t subtraction a x ( b – c) = a x b – a x c
While teaching the lesson, the teacher should consult textbook at all steps where in and whenever applicable.

Introduction

Write ‘Distributive Laws’ on the top of the board.
Ask students if they have any idea what it is?
Tell students that this law (sometimes called property) states that you get the same answer when you multiply a number by a group of numbers added together as when you do each multiplication separately, such as; 3 x (2 + 4) = 3 x 2 + 3 x 4 so the “3” can be “distributed” over the “2 + 4” into 3 times 2 and 3 times 4.
Show it with help of the following figure:
Repeat this activity for subtraction.

Development

Activity 1

Draw the following shape on the board and tell students that this figure represents the area of rectangle with length b + c and width a.
Hence area of this rectangle is = a x (b + c) or a( b + c)
This can be split into two parts as follows;

Now the sum of the area of both rectangles is a b + a c because both are parts of that rectangle, so we can write; a (b + c) = a b + ac
Give paper strips to students in groups to verify it for themselves.

Activity 2

Tell students that it is very convenient to use distributive law for quick multiplication.
Tell students that I want to multiply 12 x 19, and I used a quick method to do it. I multiplied 12 by 20. Well 12 x 20 is easy, it`s 240. But, I added one more 12 than I needed, so i`ll take it away from 240 to give me 228. =
Similarly ask students how to do;

4 x 27
= 4(20 + 7)
= 4(20) + (7)
= 80 + 28 = 108

Activity 3

Now divide students in two groups.
Each group will suggest a multiplication sum like given in the examples of previous activity, for the other group as challenge.
Other group will solve in their notebooks.
Each group will solve at least 5 questions.
Help students if they are unable to do any question.
These multiplication sums can be selected from textbook exercise as well.

Sum up / Conclusion

The Distributive Laws lets you multiply a sum by multiplying each added separately and then add the products.
Quick multiplication can be done through distributive laws.
The Distributive Property helps with mental math.
A quick multiplication is;