Lesson Notes By Weeks and Term v4 - JHS 1
Number: Ratios a nd Proportion
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Number: Ratios a nd Proportion
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Subject: Mathematics
Class: JHS 1
Term: 2nd Term
Week: 4
Grade code: B7.1.4.1.4
Strand code: 1
Sub-strand code: 4
Content standard code: B7.1.4.1
Indicator code: B7.1.4.1.4
Theme: NUMBER
Subtheme: Number: Ratios a nd Proportion
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This lesson focuses on a very powerful mathematical idea called proportional reasoning. This is not just a topic for exams; it is a skill we use every day. When you help your mother in the kitchen to prepare jollof rice for more people than usual, you use proportional reasoning. When a driver calculates how much fuel is needed for a long journey, that's proportional reasoning. When a seamstress adjusts a pattern for a different size, she is using proportion. Today, we will learn the mathematical methods to solve these kinds of problems accurately and confidently. We will learn how to find a missing number in a situation where two things change together at the same rate.
Recap: What is a Ratio? A ratio is a way to compare two or more quantities. For example, if there are 10 boys and 15 girls in a class, the ratio of boys to girls is 10:15. We can simplify this ratio by dividing both numbers by their greatest common factor (which is 5). So, the simplified ratio is 2:3. This means for every 2 boys, there are 3 girls. We can also write this as a fraction: 2/3. Main Concept: What is a Proportion? A proportion is a statement that two ratios are equal. It is like saying two fractions are equivalent.
Imagine you are mixing a drink like *sobolo*. Your favourite mix is 1 cup of sobolo concentrate to 4 cups of water. The ratio is 1:4 or 1/4.
Now, what if you want to make a larger quantity for your friends? If you use 2 cups of concentrate, how many cups of water will you need to keep the taste the same? You have twice as much concentrate, so you will need twice as much water. 2 x 4 = 8 cups of water. The new ratio is 2:8.
A proportion states that these two ratios are equal because they represent the same taste: `1/4 = 2/8`