Rule for Algebra- Understanding Why they exsist
Activity Author
Lubna Naseem
Duration
30-40 mins
Objective: Key Core Life Skill to be developed
Critical thinking, Problem Solving
Objective: Key Learning Domains to be developed
Remember, Understand, Application
Implemented this in classroom
Objectives to be achieved
Explaining the three rules of signs in algebra and why they exist like thatMaking them comfortable with using signs at the end of the class and apply it in algebra
Underlying Concept behind this activity
Make them understand that the operations are the core principles of arithmetic and algebra and they remain same for both. Coz in algebra numbers get replaced by variables bt the end results remain same. Students have to understand that subtle/ hidden concept abt algebra
Resources required for conducting the activity
Blackboard and chalk
Class Activity Details
Rule 1 Addition of two Numbers with the same sign The result is the sum of the numbers with the given sign ( the sign of the two numbers ) .
Situation 1: ++ =+
When we add two plus numbers we get a plus number
Ex : 3+6=9.
Situation 2: – – =+
When we add two minus numbers we get a minus number but the value of the answer is more than the two additives that’s why its Plus sign
Ex : -5 + – 6 = – 11 .
Example 5 + 6 + 8 = 19 . Example -5 + – 8 + – 6 = – 19 .
Rule 2 : Addition of two numbers with different signs the result is the difference between the numbers with the sign of the” bigger number ” .
Situation 3: – + = –
Ex 6 + – 9 = – 3 : Ex 19 + -5 = 14 . Ex -15 + 13 = – 2 .
In the above example the answer is decreasing therefore negative sign applies.
Note Ex : 14 – 9 is the same as 14 + – 9 = 5 . and – 7 – 5 is really -7 + – 5 = – 12
Example simplify – 6 + 9 – 7 + 3 + 6 – 8 = – 6 – 7 – 8 + 9 + 3 + 6 = – 21 + 18 = – 3 .
Note we add the minus numbers ,we add the plus numbers then tidy it up .
Rule 3 : Multiplication and signs :
The basic rules for multiplication and signs are as follows
(Minus ) x ( Minus ) = Plus . ( Minus ) x ( Plus ) = Minus , (Plus ) x (Plus ) = Plus .
This can be expressed as follows that
(a) when we multiply two numbers with the same sign we get plus
( b) when we multiply two numbers with difference signs we get a minus .
Example : – 7 x – 5 = + 35 , -7 x 5 = -35 . Example – 7. x – 4 x 3 = 28 x 3 = 84 .
Brainstorming Questions: Can you tell why in the above conditions of rule 3 results are like that
Note: if we are asked to multiply three or more numbers remember you can only multiply two numbers at a time .
Example – 4 x -3 x 5 x -2 = 12 x 5 x – 2 = 60 . x – 2 = – 120 .
Practice worksheets
You can give them sums with the above three rules for practice to be done at home
link to follow:
http://www.leavingcertsolutions.com/junior_cert_maths_higher_algebra.htm
Uploaded File
Brainstorming questions asked in class
Can you explain why the results are like that for Rule 3
Evaluation parameters to assess the understanding of the students
Accurate, Complete, Methodical, Precise, Organized
Impromptu changes made if any during activity, reasons
Any suggestions for other teachers while implementing this activity in classroom.
this class shud be taken up before the teacher begins with algebraic expressions.
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