# Lesson Plan of Distributive Law

#### Students’ Learning Outcomes

·         Verify distributive laws

#### Information for Teacher

·         Distributive law collects multiplication and addition subtraction operations:
o   Distributive law w.r.t addition x(b + c) = a × b+ a c
o   Distributive law w .r.t subtraction ax(b – c) = a × b – a x c
·         While teaching the lesson, also consult textbook at all steps where and when applicable.

#### Material / Resources

Chalk/marker, board, textbook, duster

#### Worm up activity

·         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.
Example: 3x (2+4) =3×2 +3×4 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:
3 x (2 + 4)                                                                    (3 x 2) + (3 x 4)

#### 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 + ac
·         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 as students how to do
·         Solve 2 more examples1:         4 x 27
= 4(20+ 7)
= 4(20) + (7)
= 80 + 28 = 108
Example 2:   obtain 4 x 102 using distributive law
Solution: We know, 102 = 100 + 2
So, 4 x 10 = 4 x (100 + 2)
= (4 x 100) + (4x 2)
= 400 + 8 = 408

#### 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:
4 x 53
= (4 + 50) + (4 x 3)
= 200 + 12 = 212

#### Assessment

·         Students will be given following statement questions to apply their understanding of Distributive Law.
·         Mother prepared 12 bags of sweets for birthday party of Semi. In each bag she puts 5 chocolate and 14 candies. How many sweets did mother buy?
·         A necklace made of alternating 4 grey beads and 2 black beads is shown. Explain the way one can find, how many beads are there in the necklace?