Pie charts

Habari Mwanafunzi! Let's Slice Up Some Data with Pie Charts!

Welcome, future data wizard! Have you ever wondered how to show information in a simple, colourful, and easy-to-understand picture? Imagine you're sharing a big, delicious cake with your friends. Each person gets a slice, right? Some slices might be bigger than others. A pie chart works exactly like that, but instead of cake, we are slicing up information!

Today, we are going to become experts at "baking" these mathematical pies. By the end of this lesson, you'll be able to take any set of data and turn it into a beautiful pie chart that tells a story. Ready? Let's get started!

Image Suggestion: A vibrant and colourful illustration of a Kenyan student smiling, holding a slice of a pie that is actually a colourful pie chart. The background could have subtle hints of a classroom with a chalkboard. The style should be cheerful and educational.

What Exactly is a Pie Chart?

A pie chart is a circular graph that is divided into slices, which we call sectors. The entire circle represents the total amount of something (like the total number of students in your class), and each slice represents a part or a percentage of that total.

Think about the different counties in Kenya. All 47 counties together make up the whole country. A pie chart could show the population of each county as a slice of the total population of Kenya. The bigger the population, the bigger the slice!

The most important thing to remember is that the whole circle is always 360 degrees (360°), just like a full turn!

The Key Ingredients: The Math Behind the Slices

To create an accurate pie chart, we can't just guess the size of the slices. We need to do a little bit of math. It's simple, I promise! The main goal is to convert the data we have for each item into an angle (in degrees).

Here is the magic formula you will use every time:

Angle of a sector = (Value for the item / Total of all values) * 360°

Let's break it down:

• Value for the item: This is the number for one specific category (e.g., the number of students who like Githeri).
• Total of all values: This is the sum of all the categories added together (e.g., the total number of students surveyed).
• 360°: This is the total number of degrees in a full circle.

Let's Bake Our First Pie Chart: Step-by-Step!

Let's use a real-world example that you might see in your school's dining hall.

Scenario: The head cook at Baraka High School conducted a survey to find out the favourite lunch meal for 180 Form 2 students. The results were recorded in a table.

Step 1: Look at Your Data

Here are the results from the survey:

• Githeri: 60 students
• Ugali and Sukuma Wiki: 75 students
• Rice and Beans: 30 students
• Chapati and Ndengu: 15 students

Step 2: Find the Total

First, we need to make sure the numbers add up to the total number of students surveyed.

Total Students = 60 + 75 + 30 + 15 = 180 students

Perfect! The numbers are correct. Now, let's calculate the angle for each meal.

Step 3: Calculate the Angle for Each Slice

Githeri:

Angle = (60 / 180) * 360° = 120°

Ugali and Sukuma Wiki:

Angle = (75 / 180) * 360° = 150°

Rice and Beans:

Angle = (30 / 180) * 360° = 60°

Chapati and Ndengu:

Angle = (15 / 180) * 360° = 30°

Step 4: Check Your Work!

A very important final check is to add up all your angles. They MUST equal 360°. Let's see:

Total Angle = 120° + 150° + 60° + 30° = 360°

Sawa kabisa! Our math is correct.

Step 5: Draw and Label the Chart

Now you would take a compass to draw a perfect circle, and a protractor to measure and draw each angle. Remember to label each slice clearly or use a key with different colours.

           /=========\
         /  Githeri  \
        /   (120°)    \
       |---------------|
      / Ugali & Sukuma \
     /     (150°)       \
    |--------------------|
    | Rice&Beans | C&N   |
    |   (60°)    | (30°) |
     \----------|-------/

Image Suggestion: A clear, colourful, and neatly labeled pie chart based on the "Baraka High School Favourite Lunch" data. Each sector should have a distinct colour and be labeled with the meal name and its percentage (e.g., Ugali & Sukuma Wiki - 41.7%). A small icon representing each food item could be placed next to the labels.

Reading a Pie Chart: What's the Story?

Sometimes, you will be given a pie chart and asked to interpret it. This is like being a data detective!

Scenario: The following pie chart shows how a farmer in Kiambu County uses his 20-hectare piece of land.

            /~~~~~~~~~\
          / Tea (180°) \
         /              \
        |----------------|
        | Coffee | Maize |
        | (90°)  | (54°) |
        |--------|-------|
        \ Dairy  /
         \ (36°)/
          \----/

Question: How many hectares are used for growing Maize?

To solve this, we work backwards! We use the angle for Maize to find what fraction of the total land it represents, and then multiply by the total land area.

Hectares for Maize = (Angle for Maize / 360°) * Total Hectares

Hectares for Maize = (54° / 360°) * 20 hectares

Hectares for Maize = 0.15 * 20 hectares

Hectares for Maize = 3 hectares

So, the farmer uses 3 hectares of his land for growing maize. See? You can get precise numbers just from the picture!

You're All Set!

Congratulations! You have learned the what, why, and how of pie charts. They are a powerful tool for showing information in a simple, visual way. Remember the key formula, always check that your angles add up to 360°, and don't forget to label your chart clearly.

Sasa, you are a data chef! Go on and practice by looking at data around you – maybe your own study schedule, the subjects you like, or the way you spend your pocket money. Turn it into a pie chart and tell its story!

Habari Mwanafunzi! Let's Cut a Slice of Data with Pie Charts!

Have you ever shared a birthday cake or a pizza with your friends? You cut it into slices, right? The bigger the person's appetite, the bigger the slice they might get! A pie chart works in the exact same way, but instead of sharing a cake, we are sharing and showing information. It’s a powerful way to see how a whole thing is divided into different parts. So, let's get our aprons on and get ready to "bake" some mathematical pies!

Image Suggestion: A vibrant and colourful illustration of a group of diverse Kenyan students in school uniform, happily sharing a large pizza. One student is pointing to a slice, and a thought bubble above them shows a pie chart that looks exactly like the pizza, with labels like 'Friends', 'Family', 'Me'. The style should be cheerful and educational.

What Exactly is a Pie Chart?

A pie chart is a circular graph that is divided into slices (we call them sectors) to show numerical proportion. Imagine the whole circle is 100% of something, like your total pocket money for the week. The slices show how you spend it – a slice for snacks, a slice for bus fare, a slice for saving, and so on.

The most important things to remember are:

• The entire circle represents the total amount.
• The total angle in a circle is always 360°. This is a magic number for us!
• Each slice (sector) represents a part of the total, and its size (the angle) tells us how big that part is.

        +------------------+
       /                  /
      /     Sector A     /
     /    (e.g., Snacks) \
    /                    v
   +----------------------+-------+
   |                      |        |
   |      The Whole       | Sector |
   |     Pie (Total)      |   B    |
   |        360°          |(Fare)  |
   |                      |        |
   +----------------------+-------+

How to Make a Perfect Pie Chart: A Step-by-Step Recipe

Let's work with a real Kenyan example. Imagine we asked 80 students at Umoja Primary School what their favourite local fruit is. Here are the results:

• Mangoes: 40 students
• Bananas: 20 students
• Oranges: 15 students
• Avocados: 5 students

Let's turn this data into a beautiful pie chart! Sawa?

Step 1: Find the Total

First, we confirm our total. It's the total number of students we surveyed.

40 (Mangoes) + 20 (Bananas) + 15 (Oranges) + 5 (Avocados) = 80 students

Our whole "pie" represents 80 students.

Step 2: Express Each Part as a Fraction

Next, we find the fraction of the total for each fruit.

• Mangoes: 40 out of 80 → ⁴⁰/₈₀
• Bananas: 20 out of 80 → ²⁰/₈₀
• Oranges: 15 out of 80 → ¹⁵/₈₀
• Avocados: 5 out of 80 → ⁵/₈₀

Step 3: Calculate the Angle for Each Slice (Sector)

This is the most important step! We use our magic number, 360°. The formula is:

Angle of Sector = (Fraction for the item) × 360°

Let's do the math for each fruit:

Mangoes:   (40 / 80) * 360° = 0.5 * 360° = 180°

Bananas:   (20 / 80) * 360° = 0.25 * 360° = 90°

Oranges:   (15 / 80) * 360° = 0.1875 * 360° = 67.5°

Avocados:   (5 / 80) * 360° = 0.0625 * 360° = 22.5°

Quick Check: A good way to know if your math is correct is to add up all the angles. They should total 360°.
180° + 90° + 67.5° + 22.5° = 360°. Perfect!

Step 4: Draw and Label the Chart

Now you grab a compass to draw a circle and a protractor to measure the angles. Start with a radius line (from the center to the edge), measure your first angle (e.g., 180° for Mangoes), draw the line, and then measure the next angle from there. Colour each sector differently and add a key or legend so everyone knows what each colour means.

Image Suggestion: A clear, labelled diagram showing a hand using a protractor on a circle to measure an angle for a pie chart sector. The diagram should have labels like 'Baseline', 'Center Point', 'Measuring 90°'. This visual will help students understand the practical drawing step.

Let's Interpret a Pie Chart

Drawing is only half the fun! The other half is understanding what a pie chart tells you.

Scenario: The Muranga County government spends its budget on different sectors. The pie chart below shows the spending for a year. The total budget was KSh 500 Million.

              ****************
          ****    Education   ****
        **        (180°)        **
      **                          **
     *                             *
     *                             *
    ** Health (90°)                **
     *                             *
     *---** Agriculture(45°)      *
      **--** Roads(45°)          **
        **                      **
          ****              ****
              ****************

Questions:

1. Which sector received the most funding?
2. How much money was spent on Health?

Answers:

1. Education, because it has the largest angle (180°), which is half the circle!
2. To find the money spent on Health, we calculate: (Angle for Health / 360°) * Total Budget.

   (90° / 360°) * 500,000,000 KSh = 0.25 * 500,000,000 = 125,000,000 KSh

   So, 125 Million Kenyan Shillings were spent on Health. See? You can get very precise information from a simple picture!

Summary: The Key Takeaways

Well done for making it this far! You are now a pie chart expert. Let's wrap it up:

• Pie charts show parts of a whole.
• The total circle is always 360°.
• To find the angle for a slice, you use the formula: (Value of item / Total value) × 360°.
• They are great for a quick visual comparison but can get messy if you have too many slices!

Now it's your turn to practice. Data is all around you – in sports, at home, and in school. Keep your eyes open, and you'll see pie charts everywhere!

Hongera! You have successfully completed this lesson. Keep up the great work!

Habari Mwanafunzi! Let's Slice Up Some Data with Pie Charts!

Have you ever seen a colorful circle, cut into different-sized slices like a pizza or a chapati, on TV news or in the Daily Nation newspaper? That, my friend, is a pie chart! It might look simple, but it's one of the most powerful tools in statistics for showing information at a glance. Today, we are going to become experts at reading, understanding, and even creating our own pie charts. Twende kazi! (Let's get to work!)

So, What Exactly is a Pie Chart?

A pie chart is a circular statistical graphic that is divided into slices to illustrate numerical proportion. In a pie chart, the arc length of each slice (and consequently its central angle and area), is proportional to the quantity it represents. Think of it like sharing a mandazi with your friends. If one friend is very hungry, they get a bigger piece. If another just wants a small taste, they get a smaller piece. The whole mandazi represents the total (100%), and each piece represents a part of that total.

Image Suggestion: A vibrant and colourful pie chart with 3D-effect slices. The chart is about "Favourite Fruits in a Kenyan Market" with slices for Mango, Banana, Avocado, and Orange. Each slice is a different bright colour, and there are small, realistic illustrations of the fruits next to their corresponding slices. The style should be clean and modern, like an infographic.

Why Do We Even Use Pie Charts?

Pie charts are fantastic for a few key reasons. We use them to:

• Show a 'part-to-whole' relationship. For example, how much of the family budget is spent on food versus rent versus school fees.
• Compare the popularity of different items easily. You can see the biggest slice and know it's the most popular choice immediately.
• Present data in a simple, visual way that is easy for anyone to understand, even without looking at the raw numbers.

Let's Get Cooking! How to Draw a Pie Chart

Alright, it’s time to roll up our sleeves and create our own pie chart from scratch. It’s easier than you think! We just need to follow a few simple steps. Sawa?

Real-World Example: A farmer in Uasin Gishu County, Mama Bomet, has a small shamba (farm). She has divided her land to grow different crops. She has 10 acres for Maize, 5 acres for Beans, 3 acres for Sukuma Wiki, and 2 acres for Potatoes. Let's represent this on a pie chart!

Step 1: Collect and Organize Your Data

First, we put all our information into a simple table. This makes it neat and easy to work with.

+-------------+--------------+
| Crop        | Area (Acres) |
+-------------+--------------+
| Maize       | 10           |
| Beans       | 5            |
| Sukuma Wiki | 3            |
| Potatoes    | 2            |
+-------------+--------------+

Step 2: Calculate the Total

We need to know the size of the whole "pie". So, we add up all the values.

Total Area = 10 (Maize) + 5 (Beans) + 3 (Sukuma Wiki) + 2 (Potatoes)
Total Area = 20 Acres

Step 3: Find the Angle for Each Slice

A full circle has 360 degrees (360°). To find out how big each slice should be, we use a special formula. For each item, we calculate its angle.

Angle = (Value of the Item / Total Value) * 360°

Let's calculate the angle for each of Mama Bomet's crops:

Maize:
(10 / 20) * 360° = 0.5 * 360° = 180°

Beans:
(5 / 20) * 360° = 0.25 * 360° = 90°

Sukuma Wiki:
(3 / 20) * 360° = 0.15 * 360° = 54°

Potatoes:
(2 / 20) * 360° = 0.1 * 360° = 36°

Quick Check: The angles should always add up to 360°. Let's see: 180° + 90° + 54° + 36° = 360°. Perfect!

Step 4: Draw the Pie Chart

Now for the fun part! You will need a pair of compasses to draw a perfect circle, a ruler to draw a starting line (the radius), and a protractor to measure the angles.

1. Draw a circle.
2. Draw a line from the center to the edge (the radius).
3. Place your protractor on this line and measure the first angle (e.g., 180° for Maize). Mark it and draw the line for the first slice.
4. From this new line, measure the next angle (90° for Beans). Continue until all slices are drawn.
5. Finally, label each slice clearly and give your chart a title! You can even colour-code it.

      MAIZE (180°)
     \      |      /
      \     |     /
       \    |    /
        \   |   /
         \  |  /
  . . . . . O . . . . .
           /|\
          / | \ POTATOES (36°)
         /  |  \
   BEANS(90°) | SUKUMA WIKI (54°)

    (O is the center point)

Image Suggestion: A clear, top-down photograph of a student's hands drawing a pie chart. The student is wearing a typical Kenyan school uniform. On the desk is a piece of paper with a partially drawn pie chart, a protractor placed accurately on a line, a pair of compasses, a ruler, and a pencil. The scene should look bright and focused on the learning process.

Reading a Pie Chart: The Other Way Around!

Sometimes, you are given a pie chart and asked to find the actual values. No problem!

Scenario: A survey was done in a class of 40 students at "Harambee Primary School" to find their favourite Kenyan meal. The results are shown in a pie chart where Githeri has a slice of 180°, Ugali has 90°, Pilau has 54°, and Chapati has 36°.

How many students chose Githeri?

We use a formula that is the reverse of what we did before:

Value = (Angle of the Slice / 360°) * Total Value

Let's find the number of students who love Githeri:

Number of Students (Githeri) = (180° / 360°) * 40 students
                             = 0.5 * 40
                             = 20 students

Nzuri sana! So, 20 students chose Githeri as their favourite meal. You can do the same for all the other meals.

Common Mistakes to Avoid

• Angles Don't Add Up: Always double-check that your calculated angles for all slices add up to exactly 360°.
• Forgetting Labels: A pie chart without labels or a key is useless! Always make sure people know what each slice represents.
• Using Pie Charts for the Wrong Data: Pie charts are best for showing parts of a whole (proportions). They are not good for showing changes over time (a line graph would be better for that!).

Let's Practice!

Here is a challenge for you. A family in Nairobi has a monthly income of KES 50,000. They spend it as follows:

• Rent: KES 15,000
• Food: KES 20,000
• Transport (Matatu fare): KES 5,000
• Airtime & Data: KES 2,500
• Savings: KES 7,500

Wrapping Up

You have done an amazing job today! Pie charts are not just circles and colours; they are stories told with data. They help us see the big picture quickly, from a farmer's harvest to a nation's budget. Keep practicing, stay curious, and you'll be a data master in no time. Hongera!