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+ a

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)

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 + 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?

Follow up

· 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.