LESSON PLAN OF ADDITION AND SUBTRACTION OF FRACTIONS

 

LESSON PLANNING OF ADDITION AND SUBTRACTION OF FRACTIONS

Subject Mathematics

Grade 5^th

Students` Learning Outcomes

• Add and subtract and more fractions with different denominators.

Information for Teachers

• In the begging, numbers were counted in whole. Later on, to count the part of whole, the concept of fraction was given.
• Fraction number has two parts. Upper part is called numerator and bottom part is called denominator.
• Once you understand the concept of addition of fractions with different denominators, you can directly apply the addition process in following ways: (2 / 7 ) + ( 3 / 5 )
• Find LCM of denominators and divide the LCM by denominator & multiply its quotient with respective numerators and we get: [( 2 x 5 ) + ( 3 x 7)/ 35]
• Solve the Parenthesis and we get: = [10 + 21] / 35
• Solve Braces and we get: = 31 / 35
• Teacher should also consult with textbook at all steps where and when applicable.

Material / Resources

Writing board, chalk / marker, duster, textbook

Introduction

• Draw a square on board.
• Divide the square into eight equal parts.
• Colour in 4 parts.
• Ask the students:

o   How many total parts of square? (8)

o   How many of these are coloured? (4)

o   Write it in fraction form. (4/8)

• Tell the students that upper number is called numerator and bottom number is called denominator. 
  
• Write another fraction 2/5 on board.
• Ask them: what is the denominator of this fraction?

o   Are the denominators of 4/8 and 2/5 same?

• Tell them that those fractions which have same denominators are called like fractions and which have different denominators are called unlike fractions.

Development

Activity 1

• Draw the following figure on board and discuss with students about the like and unlike fractions and how to interchange between them.

• On board discussion on “How to make equivalent fraction”?
• (This will help in addition and subtraction) 
  
• 

Activity 2

• Start the lesson by presenting a situation that involves the addition of fractions with unlike denominators and use student names from the class. For example, Bilal bought 5/6 of a kilogram of flour and Aliya bought ½ of a kilogram of flour. Record both fractions on the board.
• Ask the students:

o   Which student bought more flour Bilal or Aliya?

o   Bilal and Aliya would like to calculate that how much flour they have altogether.

• Does the situation call for addition, subtraction, multiplication or division? Why? Then ask students to estimate how much flour the two students purchased altogether / (plus) 5 / 6 + 1 / 2 = 5 + 3 / 6 = 8 / 6
• Ask students how they might represent in figure A Bilal portion of flour, 5/6 of a kg. i
• What could the whole box B represent? (One unit)
• Draw a figure like this. 
  
• Ask students what each of these parts represents (1/6 of a kg)
• How many parts could be coloured to represent Bilal share. (5)
• Demonstrate by using different colour chalks if possible. 
  
• Draw another fraction box and repeat the process with a different color [if possible] to represent the amount of flour that Aliya bought. 
  
• Ask students to refine their original estimates based on the given figure.
• Altogether, do you think they have less than 1 kg of flour, about 1 kg, more than 1 kilogram, or more than 2 kg?
• How you might add Bilal`s and Alay’s portions of flour?
• How can we add fractional amounts that are not the same size? Collect their responses, appreciate the closer one.
• Can we find an equivalent fraction for ½, whose denominator would be “6”.
• For example: 1 /2 of a kg is equivalent to 2/4 kg, but are Bilal`s and Alay’s pieces all the same size? Continue changing the denominator in the fraction until students see that 1 / 2 is also equivalent to 3/6, and that both Bilal`s and Alay’s portion can be thought of in terms of sixths. 
  
• Now that Bilal`s and Alay’s portion of flour are both in sixths of a kilogram, the pieces can be easily combined.
• Draw fraction boxes to make 1 whole.  
  
• Ask students to determine, based on the model, how much flour Bilal and Aliya have altogether. 1, 2/6 or 8 / 6
• At the end tell them that 5 / 6 + 3 / 6 = 1, 1 / 3

Activity 3

• Write one fraction addition on board and ask them to solve. For example,   1 / 3 + 1 / 4  
• Allocate time, move around the class and observe how do they attempt?
• After this check the work of all students.
• Finally ask any student to come on board and attempt that question.
• Addition of Fractions: 
  
• When adding fractions you must have a common denominator
• Write an example on the board: 3 / 6 + 1 / 5 =?
• Say: Find the smallest number which is divided by 6 and 5 both. This number is 30. Then multiply both the numerator and denominator to get 30.
• Once you have a common denominator, then add! (21 / 30)
• Assign questions to the pairs.
• Later give individual work.
• Addition of Mixed Fractions:
• Say: the rule is the same; you must have a common denominator to add fraction!
• Write an example on the board, 6, 1 / 2 + 5, 1 / 3
• Ask them, which are the whole number? (5, 6)
• Ask them to add these whole numbers? (5 + 6 = 11)
• Ask them to add fractions 1 / 2 and 1 / 3.
• Say: once you have the common denominator, add the fractions, and then add the whole number separately.
• Subtraction of Fractions:
• To subtract fractions you must have a common denominator. For this purpose, subtract both numerators and write same denominator.

Sum up / Conclusion

• With all these examples we have seen that for addition or subtraction of fractions we have to make the denominator alike.
• So let`s wrap up the day, ask students to reflect back and recall all the examples done in the class.
• To make denominator alike, we use making equivalent method, which we have already done in previous class.

Assessment

• Write down two questions on board:  1 / 2 + 4 / 7 and 3 / 5 - 2 / 6
• Ask the students to solve these on their copies.
• Round the class and assist them.

Follow up

• If we have one-half orange and one-third orange then what will be the total of these?
• If cut off one-fourth of one cake from three-fourth of that cake, then how much we have left?