Chapter 2: How Do Computers Think? 🧠
Grades 7–8 | Ages 13–14
Teacher: Mr. Yousef Younis
"Computers don't understand — they follow instructions perfectly, one step at a time."
🎯 The Big Idea
Computers don't actually "understand" anything.
They follow instructions exactly, step by step.
If the steps are clear → the computer does the job ✅
If the steps are unclear → it gets stuck ❌
Think About This:
Humans 🧠
Can guess what you mean, fill in missing info, adapt on the fly
Computers 💻
Do EXACTLY what you tell them — nothing more, nothing less
This is why programming requires precision. Every single step matters!
✅ What's an Algorithm?
An algorithm is like a recipe 📝
A clear, step-by-step list of instructions to solve a problem or complete a task.
Example: Real Life Algorithm
🦷 Brushing Your Teeth
- Put toothpaste on brush
- Brush teeth for 2 minutes
- Rinse mouth with water
- Put brush back in holder
Every algorithm has a clear beginning, specific steps, and an end goal!
💻 Computer-Style Algorithm
Here's how a computer might control a fan based on temperature:
STEPS:
1. Read temperature from sensor
2. IF temperature > 30°C THEN turn_on_fan
3. ELSE turn_off_fan
4. Wait 5 minutes
5. REPEAT from step 1
💡 Notice: The computer follows these steps in order, over and over. It doesn't "know" it's hot outside — it just checks numbers and follows rules!
Why This Works:
- Each step is clear and specific
- No guessing required
- Repeats automatically
- Makes a decision based on data
🔁 Order Matters! (Sequence)
Computers run instructions in order: 1 → 2 → 3 → 4
If you swap steps, the results change completely!
❌ Bad Example: Baking a Cake
- Put in oven and bake for 30 minutes
- Mix flour, eggs, and sugar
- Pour into pan
😱 Result: No cake! You baked an empty oven!
✅ Good Example: Baking a Cake
- Mix flour, eggs, and sugar
- Pour into pan
- Put in oven and bake for 30 minutes
🎉 Result: Delicious cake!
Sequence is everything! Computers can't "figure out" the right order — you have to tell them.
🚦 Making Decisions (IF–THEN–ELSE)
Computers make simple yes/no choices based on conditions.
The Pattern:
IF condition is true THEN
do this
ELSE
do that
Real Examples:
🔐 Password Check
IF password matches THEN
allow login
ELSE
show error message
🎮 Game Score
IF score ≥ 100 THEN
show "You Win!" 🏆
ELSE
continue game
✍️ Mini Exercise Time!
🔋 Battery Saver Challenge
Write an IF–THEN–ELSE statement for this scenario:
Scenario: Your phone needs to save battery when it's running low.
Task: If battery is less than 20%, enable power-saving mode. Otherwise, keep normal mode.
💭 Think About:
- What's the condition you're checking?
- What happens if it's true?
- What happens if it's false?
⏰ Time: 2 minutes — Write your answer on paper or discuss with a partner!
✅ Solution: Battery Saver
Here's one way to write it:
IF battery < 20% THEN
enable power-saving mode
ELSE
keep normal mode
Let's Break It Down:
- Condition: battery < 20% (checking if battery is low)
- TRUE path: Turn on power-saving mode
- FALSE path: Stay in normal mode
This is exactly how your phone's battery saver works! It constantly checks the battery level and makes this decision.
🔄 Repeating Steps (Loops)
Sometimes computers need to repeat the same steps over and over until something changes.
Two Types of Loops:
1️⃣ WHILE Loop (repeat until condition changes)
In plain words:
"While there are unread messages, keep doing: open one message, mark it as read."
WHILE unread_messages > 0
open next message
mark as read
2️⃣ FOR Loop (repeat a specific number of times)
In plain words:
"Do this 10 times: add one star to the screen."
FOR 10 times
add one star ⭐
🔄 Loops in Real Life
Example 1: Waiting for Download ⬇️
WHILE download not complete
show progress bar
check download status
wait 1 second
The computer keeps checking until the download finishes!
Example 2: Countdown Timer ⏱️
FOR 10 times
display number
subtract 1
wait 1 second
THEN show "Time's up!"
Repeats exactly 10 times: 10... 9... 8... 7... etc.
Loops save time! Instead of writing the same instruction 100 times, just use a loop.
🗺️ Visualizing Computer Logic (Flowcharts)
Flowcharts help us see the flow of computer thinking using boxes and arrows.
The Pattern: Input → Process → Output
Every computer program follows this basic flow!
Flowchart Shapes:
Do Something
Rectangle shape
Make Decision?
Diamond shape
🔐 Example: Login Flowchart
Let's visualize how a login system works:
START
↓
Get username & password
↓
Is password correct?
✅ YES
Open home screen
↓
END
❌ NO
Show error message
↓
Ask to try again
💡 Notice: The flowchart splits into two paths based on the YES/NO decision. This is how IF-THEN-ELSE works visually!
🧪 Quick Check! (2 minutes)
Question 1:
An algorithm is…
a) A random idea
b) A clear step-by-step plan ✅
Question 2:
Fill in the blanks:
IF traffic light is red THEN stop
ELSE go
Question 3:
True or False:
"Computers can guess what you mean."
FALSE ❌ — Computers only do exactly what they're told!
🎯 Putting It All Together
A good algorithm uses all three concepts:
1️⃣ Sequence (Order)
Steps happen in the right order
2️⃣ Decisions (IF-THEN-ELSE)
Make choices based on conditions
3️⃣ Loops (Repetition)
Repeat steps as needed
Example: Smart Home Thermostat 🌡️
START
REPEAT forever:
1. Read current temperature
2. IF temperature > 25°C THEN
turn on air conditioning
3. ELSE IF temperature < 18°C THEN
turn on heating
4. ELSE
keep everything off
5. Wait 10 minutes
END
This uses sequence, decisions, AND loops — just like real smart home systems!
🏠 Homework Time!
🥪 Make a Sandwich Algorithm
Your task: Write a step-by-step algorithm for making your favorite sandwich!
Requirements:
✅ Part 1: Basic Steps (5-7 steps)
Write the steps in order. Be specific!
Example start: 1) Get two slices of bread, 2) Put peanut butter on one slice...
✅ Part 2: Add ONE Decision (IF-THEN-ELSE)
Include a choice in your algorithm.
Example: "IF no cheese available THEN use tomato ELSE use cheese"
🌟 Part 3: OPTIONAL Challenge
Draw a small flowchart with boxes and arrows!
💡 Homework Tips & Examples
Good Algorithm Example: PB&J Sandwich
SANDWICH ALGORITHM:
1. Get two slices of bread
2. Get peanut butter and jelly
3. Spread peanut butter on slice 1
4. IF jelly jar is empty THEN
use honey instead
ELSE
use jelly
5. Spread jelly (or honey) on slice 2
6. Put the two slices together
7. Cut in half
8. ENJOY! 🎉
Pro Tips:
- Be specific! "Put stuff on bread" is too vague
- Think about order — what HAS to happen first?
- Your IF-THEN-ELSE should make sense (like checking if you have ingredients)
- Test it! Could someone else follow your steps?
🌟 Why Does This Matter?
Everything runs on algorithms! 🚀
📱 Your Phone
Algorithms decide which apps to show, how to save battery, when to update
🎮 Video Games
Every character, enemy, and event follows programmed algorithms
🚗 Self-Driving Cars
Use algorithms to detect obstacles, make decisions, and navigate safely
🎵 Music Apps
Algorithms recommend songs based on what you've listened to before
Understanding algorithms is the first step to understanding how ALL technology works!
👀 Sneak Peek: Real Programming
Here's what the fan algorithm looks like in actual code (Python):
import time
while True:
temperature = read_sensor()
if temperature > 30:
turn_on_fan()
else:
turn_off_fan()
time.sleep(300) # wait 5 minutes
See the patterns?
- while True = loop forever
- if = decision making
- Everything happens in sequence
- Same concepts, just different syntax!
You're already thinking like a programmer! 🎉
📚 Chapter Summary
What We Learned:
🧠 How Computers Think
Computers don't understand — they follow precise instructions step-by-step
📝 Algorithms
Step-by-step instructions to solve problems (like recipes!)
🔁 Sequence
Order matters! Steps must happen in the right order
🚦 Decisions
IF-THEN-ELSE lets computers make choices based on conditions
🔄 Loops
Repeat steps multiple times (WHILE and FOR loops)
🗺️ Flowcharts
Visual way to see algorithm flow with boxes and arrows
🔮 Coming Up Next...
Chapter 3: Let's Start Coding! 💻
Now that you understand how computers think, it's time to actually program them!
🎨 Scratch
Visual programming with blocks
🐍 Python Basics
Your first text-based code
🎮 Make a Game
Build something fun!
Get ready to become a creator! 🚀
💬 Let's Discuss!
Think about these questions:
1. What's one algorithm you follow every day without thinking about it?
2. Why is it important that computers can't "guess" what you mean?
3. Can you think of a situation where changing the order of steps would cause a problem?
4. What's something you wish computers could do that they can't (yet)?
💭 Remember: Every app, game, and website you use is built from algorithms just like the ones we learned today!
Great Job Today! 🎉
— Mr. Yousef Younis
Stay curious. Keep questioning. Start creating! ✨
Don't forget your homework! 📝
Questions? Let's talk! 💬
See you next time when we start coding! 🚀