Brownie Badge: Coding Basics

Today we're going to learn about computer programming! We'll learn what a program is, and some of the ways that people give instructions to computers. We'll also learn a little about how computer programming started, and about some of the women in computer science at its very beginnings and today.

About Programming

Programming is writing instructions that tell a computer how to do something. Apps and games on a tablet or a phone are programs. So are webpages. But less-noticeable programs are everywhere, too: they control how a car's engine works, tell traffic lights when to turn red or green, add up your bill at a restaurant. Here are some things that I like about programming:

You can make useful things to help yourself and other people.
You can make fun things, to make people smile or encourage creativity.
Programmers (mostly!) love to share how to do things. Many programs are "open source", meaning that anyone can look at, use, and even change the code that makes the program work.
Programming is all about iterating: trying your program, seeing something you can make better, making the change, and then checking to see if you like the result. For me (and not just me!), this feels fun and creative!

Some Women Programmers

Ada Lovelace: Around two hundred years ago a man named Charles Babbage had the idea to make a machine that used metal gears to do math. Many people consider this "Analytical Engine" to be the first computer, but he was unable to build the machine during his lifetime. Ada Lovelace was 18 years old when she learned about the machine at a lecture given by Babbage. She was the first person to realize that a computer could work with words and music in addition to numbers! Even though the machine had not been built yet, Ada Lovelace wrote an algorithm for using the machine to calculate a special list of numbers that help to do things like measure shapes. Today, this is known as the first computer program!
Grace Hopper: About 75 years ago, the first computers that ran on electricity had been built, and were mostly used by the military. Giving these computers instructions—programming them—was very hard because every computer understood different instructions, and every step had to be written as "machine code", a list of numbers that the computer could understand. Grace Hopper was a college math professor who joined the Navy during World War II, when she worked on a very early computer called the Mark I. She came up with the idea of a programming language that would let people write computer instructions using regular English words. People told her this idea was crazy! To make it work, she wrote a program (the hard way!) to turn these human-readable words into the "machine code" that computers could use. Today, we call this kind of program a "compiler".

Now, almost all programs are made in easier-to-read "programming languages" and then translated into computer machine code by a "compiler"; and Grace Hopper wrote the first one!
Katherine Johnson: At roughly the same time that Grace Hopper was inventing modern computer programming, there weren't yet enough electronic computers to do all of the math that groups like the US Army and NASA needed. So they hired people to do this work, and those people were called... "computers"! This work was not always fun, but it needed a lot of smart people. So they hired many kinds of people who were often discriminated against, like women, black people, and Jewish people. That's how Katherine Johnson was hired by NASA. Even while segregated into a separate group of Black workers, Katherine's math skills were so highly respected that people trusted her more than they did the electric computers of that time. In 1962, astronaut John Glenn (the first American to orbit the Earth) asked her to personally verify the flight path of his first launch into space.
Donna Auguste: 35 years ago, you couldn't use a phone to draw a picture, check your calendar, play a game, or take notes; they could only make calls! Donna Auguste was one of the engineers who helped change that. At Apple, she led a team of software engineers building the Apple Newton, a handheld computer you could write on with a special pen. It was one of the very first computers small enough to carry in your bag, and it helped lead the way to the smartphones and tablets we use today.

Later, Donna started her own company called Freshwater Software, which made tools to help keep websites running smoothly. She was the first Black woman to earn a PhD in computer science from Carnegie Mellon University — right here in Pittsburgh!
Taylor Poindexter: Taylor Poindexter is a programmer who's working today, as an Engineering Manager at the music service Spotify. She shares her insights and perspective online, especially about managing engineers and some of the quirks of many computer jobs (like being paid with company "stock"). I (and about 50,000 other people!) follow her on Twitter.
Mira Murati: Over the last few years, the hottest topic in computer science has been AI. Who hasn't heard of ChatGPT? Mira Murati led the work on ChatGPT and other projects as the Chief Technology Officer of OpenAI starting in May 2022. After she left in late 2024, she launched an AI startup called Thinking Machines Lab.

Coding Vocabulary

Algorithm Example: Walk in a Square

This word still sounds, to me, like it should be something very complicated! But it’s just a list of instructions to complete a certain task or solve a problem. Think of things that you usually do the same way each time: getting ready for bed (say goodnight, brush teeth), going to the grocery store (walking/driving directions), making a little drawing you like to do. You follow an algorithm to make a paper fortune teller, and follow a different algorithm to use one. Opal has a few different algorithms for drawing cats. I have a different algorithm for cracking eggs than my Mom does.

Programmers try to find the best way to do something for specific situations. How exact do we need to be? How fast does it need to be? How many times do we have to do it? This can be a fun puzzle to solve, and is one kind of thing that programmers debate with each other.

Event Example: Click Event

An event is when a program has to react to something outside of the program. Often this is a person doing something, like pressing a key, moving the mouse, or tapping on a screen. But lots of other things can be events, too: a different program finishing a task, the clock reaching a certain time, or a loud sound happening. Programs are setup so that when one of these events happens, an algorithm—a part of the program—runs. At school, when the fire alarm goes off (an event), students stop what they’re doing and follow their teacher outside (an algorithm).

Loop Example: Walk in a Square Loop

Loops—doing the same steps over and over again—are everywhere in computer programs. A loop might be how a program waits for an event: by checking, over and over again, “is someone pushing the space bar?” To animate moving a picture across the screen, a program might have a loop where the picture is moved a tiny bit every fraction of a second. You could make your own timer program by having a loop that adds 1 to the total number of seconds, over and over. Sometimes a loop can do the same steps each time, but to a new “thing” each time. When your class does show-and-tell, the same thing happens over and over—someone comes to the front, talks about something, and answers a few questions—but each time it happens with a different kid.

Variable Example: Count Square Sides

A variable is a container for something. It could be a number, a word, a sentence, a picture, a list of things, a button on the screen—all kinds of things. A program can put things into this container, and it can use whatever is in the container. In the timer program, the “total number of seconds” would be a variable. To have a computer say hello to someone, you could write a simple program that stores and then uses a variable:

Step 1: “What is your name?”
Step 2: Someone types in, “Sean”.
Step 3: The program puts “Sean” in a variable called “name”.
Step 4: The program tells the computer to say, “Hello [name], nice to meet you!” Because the “name” variable has “Sean” in it, the computer says, “Hello Sean, nice to meet you!”

🐱 Scratch Projects 🐱

For Next Week

Original Snake Game on Scratch by Eivinm

Snake Remix by Sean & Opal