Variables and data types

This lesson focuses on variables and data types. Interdisciplinary approaches reveal connections that single-subject study might miss.

In programming, a variable is a named storage location that holds a value which can change during program execution. You declare a variable by giving it a name and often a type. Data types specify what kind of value a variable holds: Integer (whole numbers: 5, -3, 100), Float/Double (decimal numbers: 3.14, -0.5), String (text: "Hello", "abc123"), Boolean (true or false), List/Array (ordered collection of values). Type matters because it determines what operations are valid: you can multiply two integers, but multiplying two strings is an error. Naming conventions: use descriptive names (studentAge instead of x), use camelCase or snake_case consistently. Variables store user input, calculation results, and program state. Understanding data types prevents common bugs and helps you choose the right tool for the job.

As you engage with this material, consider both the theoretical foundations and practical applications. Think critically about how this concept builds on prior knowledge and where you might apply it beyond the classroom.

Challenge yourself to go beyond memorization—seek to understand the "why" behind the processes and principles.