ClassX Video Lessons Youtube Channel Code.org CS Principles: Conditionals – Part 1 Boolean Expressions
When you’re programming, you often need to figure out if something is true or false. This helps the computer decide what to do next. Imagine you’re trying to find out if someone is old enough to vote. The computer uses something called a boolean expression to make this decision. Think of it like a yes or no question that the computer can answer. It’s called “boolean” because it’s named after George Boole, a mathematician who worked with true and false values.
Let’s look at the voting example. You might have a boolean expression that checks if a person’s age is 18. If the age is 18, the expression is true; if not, it’s false. In programming, you use a double equals sign (==) to check if two things are equal. Be careful not to confuse this with a single equals sign (=), which is used to assign a value to a variable.
Besides checking for equality, you can also compare values to see if one is greater than or less than another. These are called comparison operators. For example, if you ask if 3 is less than 2, the computer will say false because that’s not true. These operators help the computer answer questions with true or false.
In our voter registration example, it’s not just 18-year-olds who can vote; anyone 18 or older can. So, you would use a comparison operator to ask if the user’s age is greater than or equal to 18. If the answer is true, the computer can then display the registration information. This is just the beginning of how you can use boolean expressions to make decisions in programming. We’ll explore more about this in the next lesson.
==) and the single equals sign (=)?Write a simple program in your preferred programming language that asks the user for their age and then uses a boolean expression to determine if they are eligible to vote. Use comparison operators to check if the age is 18 or older. Share your program with a classmate and discuss how it works.
Work in pairs to find examples of boolean expressions in everyday life. For instance, consider questions like “Is it raining?” or “Is the store open?” Write down at least five examples and explain how they relate to true or false values. Present your findings to the class.
Participate in a relay race where each team member must solve a boolean expression problem using comparison operators. For example, determine if a number is greater than another or if two values are equal. The first team to correctly solve all problems wins. Reflect on the strategies used during the race.
Create a flowchart that uses boolean expressions to make decisions. Choose a scenario, such as planning a day out based on weather conditions. Use comparison operators to decide the flow of actions. Share your flowchart with the class and explain your decision-making process.
Write a short story where the main character uses boolean expressions to make decisions. Incorporate at least three different boolean expressions and describe how they influence the character’s choices. Share your story with a partner and discuss the role of boolean expressions in decision-making.
Here’s a sanitized version of the provided YouTube transcript:
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When programming, it is often necessary to establish whether something is true or false so that a computer can make decisions about what actions are appropriate to take next. For example, when deciding whether to provide voter registration information, the computer must first determine if the person is old enough to vote. This is done using what programmers call a boolean expression. You can think of it like a yes or no question that the computer can evaluate. It’s called a boolean because it’s named after the mathematician George Boole, who made many discoveries related to working with binary true or false values.
In the voter registration example, your boolean expression might look like this: it asks if the value stored in the variable “age” is equal to 18. If it is, then the statement is true; otherwise, the statement is false. Remember, the double equals sign is the equality operator; it asks if two things are equal or not. If you are using a single equal sign, you are using the assignment operator to set the value of a variable, which is something else entirely.
In addition to the equality operator, we can ask questions about whether one value is greater than or less than another value, and these are called comparison operators. If you saw the statement “3 less than 2,” you might think something was wrong, but in programming, you use comparison operators to ask the computer questions that it can answer with true or false. So, with this line, the computer sees you asking if 3 is less than 2; the answer in this case is no, or false.
We can use a comparison operator in our voter registration example to make the program even more accurate, because it’s not just 18-year-olds who can vote; it’s anyone whose age is 18 or older. So the question you’d want the computer to evaluate should be: is the user’s age greater than or equal to 18? Now that we can express the question, we can have the computer actually do something depending on whether the answer is true or false, such as displaying the registration info if true. We’ll learn more about how to do that next.
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This version maintains the original content while ensuring clarity and coherence.
Boolean – A data type that can hold one of two possible values: true or false. – In programming, a boolean is often used to control the flow of a program by making decisions.
Expression – A combination of variables, operators, and values that produces a result. – In coding, an expression like “5 + 3” evaluates to the value 8.
True – A boolean value indicating that a condition or statement is correct or valid. – The statement “5 is greater than 3” evaluates to true in a boolean context.
False – A boolean value indicating that a condition or statement is incorrect or invalid. – The expression “10 is less than 5” evaluates to false.
Programming – The process of writing instructions for a computer to perform specific tasks. – Learning programming languages like Python can help you create your own software applications.
Comparison – An operation that compares two values and returns a boolean result. – In coding, a comparison like “x == y” checks if the value of x is equal to the value of y.
Operators – Symbols or keywords used in programming to perform operations on values or variables. – Arithmetic operators like “+” and “-” are used to perform mathematical calculations.
Value – A specific piece of data, such as a number or string, that a variable can hold. – In the code “let age = 15;”, the value of the variable age is 15.
Age – A variable often used to represent the number of years someone or something has existed. – In a program, you might use the age variable to determine if someone is eligible for a discount.
Vote – A decision-making process where individuals express their choice or opinion, often used in programs to simulate elections or polls. – A simple program can count the number of votes each candidate receives in an election.
