Lesson Plan of Distributive Law
Mathematics Grade V
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+ ac
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)
· 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.
· 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
· 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
· 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?
· Solve following questions by applying Distributive Laws.
1. In each fish tank there are 7 gold fish and 6 black fish. There are 8 fish tanks. How many fish are there altogether?
2. There are 3 tables. On each table there are 6 lemons glasses and 5 cold drink bottles. How many drinks are there altogether?
3. Assign some questions from textbook to do as homework.