Students` Learning Outcomes
- Solve real life problems involving direct and inverse proportion [by unitary method]
Information for Teachers
- In unitary method we deal with the following;
§ Finding the price of more things when price of one thing is given.
§ Finding the price of 1 thing if price of more things are given.
§ Finding the price of given number of things if the price of other number of same things is given.
§ During lesson where necessary also consult with textbook.
Material / Resources
Writing board, chalk / marker, duster, chart paper, packets or tins of food items, textbook
Introduction
- Show students a packet of juice and read the information for ingredients.
- The label on juice pack shows this information
- Apple juice 440 ml. each 440 ml provides;
o Energy 226 calories.
o Carbohydrates 6.6g.
o Vitamin C 20 mg
- Ask the students that if 440 ml of juice provides 226 calories how many calories 100 ml of juice will provide?
- Ask students to decide is it direct or inverse proportion question, can they show the working? If they are unable to do, then show working on the board.
- Solution:
440 ml of juice contains calories = 226
1 ml of juice contains calories = 226 + 440
100 ml will contain = 226/440 x 100 = 56.5 cal.
- Ask again is it direct or inverse proportion and why?
Development
Activity 1
- Discuss the following questions with the whole class.
- What is ratio?
o A ratio shows the relative sizes of two or more values.
o Ratio means a relation between part to part or part to whole.
- What is proportion?
o When two ratios are equal they are said to be in proportion.
- If increased in one quantity causes decrease in other quantity or decrease in one quantity, then we say that both quantities are inversely related.
- Two values are in “direct proportion” with each other if the following relationship holds: whenever one variable doubles, the other variable doubles, the other variable doubles. Whenever one variable triples, the other variable triples and so on.
- Ask the students “Do you remember the proportion tables we did in the previous lessons?”
- Show them following tables and recollect the information about direct and inverse proportion.
- Solve table 2 on the board with the help of the students.
- Change the number of workers and practice further.
- After completing the examples give students in pairs, questions from textbook exercise.
- While students are working, keep roaming in the class, correct students if they make any mistake.
Activity 2
- Write some statements of the questions for direct and inverse proportion on paper slips.
- o These questions can be taken from textbook or you can make this yourself.
- Prepare enough slips that each student gets one slip.
- Distribute these slips in the students.
- Ask students to read the statement, write is it direct or inverse proportion? And then solve the question.
- Collect back the solved slips shuffle and redistribute among students, to read and check the question of each other.
Sum up / Conclusion
- Conclude the lesson with the following points;
o All mathematical concepts are lying as situations in out daily life.
o When two values are increasing or decreasing at the same time in the same ratio, it is direct proportion.
o When two values are in relation such that one value increases other decreases, it is inverse proportion.
Assessment
- Ask students to solve the following questions in their notebooks.
Follow up
- Ask students to suggest solutions for following situations;
Ask students to suggest solutions for following situations;
