Lesson Plan of Order of operation: BOD MAS rule
Mathematics Grade V
Students’ Learning Outcomes
· Recognize BOD MAS rule, using only parentheses ()
· Carryout combined operations using BOD MAS rules.
Information for Teacher
BOD MAS: is a supportive abbreviation meaning brackets, order, division, multiplication, addition and subtraction, confirming that equation steps are completed in the correct order. A mathematical question with manifold operations may give different answers be liable on the order in which it is solved.
Concept Map
Operations
· “Operations” mean things like add, subtract, multiply, divide, squaring, etc. If it isn’t a number it is perhaps an operation.
· But, when you see something like…
· 7 + (6 × 52 + 3)
· … What part should you calculate first?
· Start at the left and go to the right?
· Or go from right to left?
· Calculate them in the wrong order, and you will get a wrong answer!
· So, long ago people agreed to follow rules when doing calculations, and they are:
Order of Operations
· Do things in Brackets First
· yes 6 × (5 + 3) = 6 × 8 = 48
· not 6 × (5 + 3) = 30 + 3 = 33 (wrong
· Exponents (Powers, Roots) before Multiply, Divide, Add or Subtract
· yes 5 × 22 = 5 × 4 = 20
· not 5 × 22 = 102 = 100 (wrong)
· Multiply or Divide before you Add or Subtract
· yes 2 + 5 × 3 = 2 + 15 = 17
· not 2 + 5 × 3 = 7 × 3 = 21 (wrong)
· Otherwise just go left to right
· yes 30 ÷ 5 × 3 = 6 × 3 = 1
· not 30 ÷ 5 × 3 = 30 ÷ 15 = 2 (wrong
How Do I Remember It All…? BOD MAS!
· B: Brackets first
· O: Order (i.e. Powers and Square Roots, etc.)
· D: Division (left to -to – right)
· M: Multiplication (left -to – right)
· A: Addition (left -to – right)
· S: Subtraction (left -to – right)
· What about 7 + (6 × 52 + 3)?
· 7 + (6 × 52 + 3)
· 7 + (6 × 25 + 3) Start inside Brackets, and then use “Orders” First
· 7 + (150 + 3) Then Multiply
· 7 + (153) Then Add
· 7 + 153 Brackets completed, last operation is add
· 160 DONE!
· Parentheses are used in math to show a part of a math expression or equation that must be solved first, before any other calculation are done.
· In this lesson we will use only parentheses () as brackets.
· While teaching the lesson, also consult textbook at all steps where and when applicable.
Material / Resources
Board, marker, textbook
Worm up activity
· Introduce to the students that math operations tell whether to add, subtract, multiply or divide and parentheses tell which operation is to be done first.
· Write 3 + 2 x 4 = –—— on board
· Write 20 as answer and ask who is agreeing?
· Write 11 as answer and ask who agrees or disagree?
· What are we to do – how can there be two answers in math?
· Explain the rule that we do multiplication first, addition second.
· Ask can I make 3 + 2 x 4 = 20? True
· Tell the students that we follow the order like:
1. B: brackets first
2. O: orders (Powers and Square roots etc.)
3. D: Division
4. M: Multiplication
5. A: Addition
6. S: Subtraction
· Explain to the students that:
· Parentheses (), can be used in math to show which part of the math expression should be done first. i.e. 8 – 5 + 1 and 8- (5+1). The only difference between these two expressions is the parentheses.
· Operation given in parentheses should be solved first.
Development
Activity 1
· Tell the students that we do operation on numbers. We add, subtract, multiply divide, but what to do if we have more than one operation to do at a time?
· How do we solve this: 3 – 5 ÷ (1 + 4) =?
· Let’s put BOD MAS into practice.
· Repeat the acronym with whole class i.e. (), OF, ÷,x, +,-,
· All is to do calculations in this order and solve the question.
· Write following examples on the board and solve with help of the students:
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21 + 14 ÷ 7 =
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(21 + 2 = 23)
(35 ÷ 7 = 5)
(3 x 3 =9)
(3 + – 6 = 2)
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21 + 14 ÷ 7 =
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3 x (5 – 2) =
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3 + 5 – (2 + 4) =
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· Write first example on the board refer to the BOD MAS rule and ask
o Do we have any (parenthesis)? (No)
o Do we have any order or powers? (No)
o What to do first addition or division? (division)
· Similarly discuss all the examples on board with students.
Activity 2
· Write on the board and explaining (8 – 4) + 5 x 8
· Parentheses come first, so 8 – 4 = 4.
· Replace in the expression with 4, where (8 – 4) was, so: 4 + 5 x 8.
· This contains addition and multiplication. Multiplication comes before addition, so 5 x 8 = 40. Replace 40 with 5 x 8 in the sentence
· That leaves 4 + 40. Finally, add 4 + 40 = 44. Sole few more same examples on the board with help of the students.
· Divide class in groups of four and distribute mathematical sentences written on paper pieces. Each group will get the required result by applying brackets e.g.
· Groups will swap their sheets after completing for the peer checking.
Activity 2
· Divide class into pairs
· Write numbers from 2 – 9 on paper slips fold them and put them in a box.
· Ask each pair to take one paper slip.
· Give them instruction that they have to use the number and operations to get the answer equal to 1.
· For example if they have got 4, they have to use 4 four times and get answer equal to like: ( 4 ÷ 4) + 4 – 1
· Similarly find an expression to make the number equal to 0.
· Time the activity.
· If students don’t get the answers. Solve on the board with the help of the students.
· This will give them extensive practice with application of BOD MAS.
Sum up / Conclusion
· Parenthesis is used to show what should be done first in arithmetic expression.
· Parenthesis ( ) are the most frequently used group symbol.
Assessment
· Give the following questions to solve individually.
Follow up
· Make 5 different arithmetical expressions using all operations and parenthesis, giving answer equal to 5 for each expression
