Lesson 1: What Computers Actually Do
About 15-20 minutes -- Screen-free lesson
What You Will Learn
By the end of this lesson, you will be able to:
- Explain what a computer really does (it follows instructions!)
- Understand that computers do not think, guess, or feel
- Name things around you that have computers inside them
- Say what the word "algorithm" means in your own words
What Is a Computer, Really?
You probably use computers every day. Maybe you play games on a tablet, watch videos on a phone, or use a laptop for school. But have you ever stopped to think about what a computer actually does?
Here is the big secret: a computer is a machine that follows instructions. That is it. That is the whole thing. A computer does not think. It does not have ideas. It does not get creative. It just does exactly what it is told to do, one step at a time.
Computer: A machine that follows a list of instructions very quickly and very accurately. It does exactly what it is told -- nothing more, nothing less.
Talk About It
Ask your child: "If a computer only follows instructions, who do you think writes those instructions?" The answer is: people do! People who write instructions for computers are called programmers or coders.
Computers Are Everywhere
When you hear the word "computer," you might think of a laptop or a desktop with a screen and keyboard. But computers are hiding in lots of places you might not expect!
Computers You Might Not Know About
- Traffic lights -- A computer inside tells the lights when to change from red to green
- Microwaves -- A computer inside counts down the time and controls the heat
- Cars -- Modern cars have dozens of computers controlling the engine, brakes, and more
- Washing machines -- A computer decides how long to spin and when to add water
- Video game controllers -- A computer reads your button presses and sends them to the game
Unplugged Activity: Computer Hunt
Walk around your house with your child. How many things can you find that have a computer inside? Look for anything with buttons, a screen, or a timer. Try to find at least 10 items!
Bonus: For each item you find, ask: "What instructions does the computer inside this thing follow?"
Computers Do Not Think
This is one of the most important ideas in this whole course. Pay close attention:
Computers do not think. They do not guess. They do not figure things out on their own. A computer can only do what someone has told it to do. If nobody gives it instructions, it just sits there doing nothing.
How Are Computers Different From People?
Imagine you ask a friend to get you a glass of water. Your friend knows what a glass is. They know where the kitchen is. They know how to turn on the faucet. You do not have to explain every tiny step.
But a computer is different. If you told a computer to "get a glass of water," it would not know what to do. You would have to tell it every single step:
- Stand up
- Turn left
- Walk forward 10 steps
- Open the cabinet
- Pick up a glass with your right hand
- Close the cabinet
- Turn right
- Walk forward 3 steps
- Put the glass under the faucet
- Turn the faucet handle to the left
- Wait 5 seconds
- Turn the faucet handle to the right
And even then, you would need even MORE steps! Computers need every tiny detail spelled out.
Talk About It
Ask your child: "What would happen if we forgot step 12 (turning off the faucet)?" This helps them understand that missing even one instruction can cause big problems.
What Is an Algorithm?
When you make a list of steps to do something, that list has a special name. It is called an algorithm.
Algorithm: A list of steps that tells you exactly how to do something. The steps must be in the right order and must be clear enough that anyone (or any computer) can follow them.
You already use algorithms every day, even if you did not know the word! Here are some algorithms you might recognize:
- A recipe for baking cookies (step 1: gather ingredients, step 2: preheat oven...)
- Directions to get to school (turn left on Main Street, go straight for two blocks...)
- The rules of a board game (first shuffle the cards, then deal 7 cards to each player...)
- Your morning routine (wake up, brush teeth, get dressed, eat breakfast...)
Unplugged Activity: Write Your Own Algorithm
Pick one of these activities and write down every step needed to do it:
- Brushing your teeth
- Making a bowl of cereal
- Getting ready for bed
- Building a tower with blocks
Try to write at least 8 steps. The more detail, the better! Remember, a computer would need every tiny step.
Why Does Order Matter?
When you follow an algorithm, the order of the steps is very important. Doing things in the wrong order can give you a very different (and often very wrong!) result.
Sequence: The order that steps happen in. In coding, doing things in the right sequence is one of the most important skills.
What Happens When the Order Is Wrong?
Imagine you are making a peanut butter sandwich. Here are two different sequences:
Correct order:
- Take out two slices of bread
- Open the peanut butter jar
- Spread peanut butter on one slice
- Put the other slice on top
Wrong order:
- Put the other slice on top
- Spread peanut butter on one slice
- Open the peanut butter jar
- Take out two slices of bread
The second version does not make any sense! You cannot put a slice on top before you have the bread out. Order matters.
Try It: Mixed-Up Steps
Here are the steps for washing your hands, but they are all mixed up. Can you put them in the right order?
- Dry your hands with a towel
- Turn on the water
- Rub your hands together for 20 seconds
- Put soap on your hands
- Rinse the soap off
- Turn off the water
- Turn on the water
- Put soap on your hands
- Rub your hands together for 20 seconds
- Rinse the soap off
- Turn off the water
- Dry your hands with a towel
What Is an Instruction?
Each single step in an algorithm is called an instruction. A good instruction tells you exactly one thing to do.
Instruction: One single step that tells someone (or a computer) exactly what to do. Good instructions are clear, specific, and describe just one action.
Good Instructions vs. Bad Instructions
Bad instruction: "Make breakfast."
This is too vague! What kind of breakfast? What do you need? Where is the food?
Good instructions:
- Open the refrigerator door.
- Take out the milk carton.
- Close the refrigerator door.
- Get a bowl from the cabinet above the sink.
- Get the cereal box from the pantry.
- Pour cereal into the bowl until it is half full.
- Pour milk over the cereal.
See the difference? Each step is clear and specific.
Talk About It
Ask your child: "Can you think of a time when someone gave you instructions that were confusing? What made them hard to follow?" This helps them see why clear instructions matter.
Check Your Understanding
Try these questions to see what you have learned:
1. What does a computer actually do?
2. What is an algorithm?
3. Why does the order of instructions matter?
4. Name two things in your house that have a computer inside them.
Key Takeaways
- A computer is a machine that follows instructions. It does not think on its own.
- Computers are inside many things you use every day, not just laptops and phones.
- An algorithm is a list of steps that tells how to do something.
- The sequence (order) of steps matters a lot.
- Each single step is called an instruction. Good instructions are clear and specific.
- People called programmers write the instructions that computers follow.
Ready for More?
Next Lesson
In Lesson 2, you will practice giving precise instructions with the famous peanut butter sandwich challenge!
Start Lesson 2