Chapter 1.2 - Getting Started

Time Estimate: 45 minutes

1.2.1. Introduction and Goals

Let's do some programming

Thunkable is based on a block platform named Blockly. This demo is from Code.org's Hour of Code activity -- maybe you've seen it before? It will help you get a sense of the type of programming you will be doing in this course. It lets you write small Blockly programs (called scripts) to solve Maze puzzles. Can you solve all 20 problems?

Click here to get started!

1.2.2. Learning Activities

Algorithms and Programs

As you learned in that activity, an Algorithm is a sequence of precise instructions that solves some problem or performs some computation. A program is an algorithm that is written in a programming language that runs on a computer and is often referred to as software. A program can be described by what it does and how the program statements accomplish its function. Each of the levels in the previous activity contained code segments, which are collections of program statements that are part of a program.

The scripts you created in the Maze demo contain all the essential control structures that programmers use to design algorithms:

• Sequence - An algorithm is a sequence of precise statements (blocks).

• Selection (if/else) - An algorithm can select between two alternative paths based on some condition.

• Repetition or Iteration (repeat) - An algorithm can repeat a sequence of statements.

Algorithms are Everywhere

Now that you've been introduced to the term algorithm and have an initial idea of what it means, you're going to discover algorithms everywhere. As you've grown up, you've learned all sorts of algorithms to solve everyday problems. For example, certainly we all know how to tie our shoelaces. But can you tie your shoelaces in 2 seconds? You could if you follow this algorithm:

Tie a Shoelace in 2 Seconds Activity: 1.2.2.1 YouTube (_aAeI7p-Tkc)

Here's an interesting fact: Computer scientists have proved that sequence, selection, and repetition are sufficient to build any algorithm that can be thought of. In other words, any algorithm can be expressed using only sequence, selection, and repetition.

Food for Thought

Computer scientists write algorithms to solve problems. And we know now that sequence, selection, and repetition are sufficient to express any algorithm we can think of.

Are there algorithms we can't think of? Or, to put that another way, are there problems that can't be solved by an algorithm? What do you think?

That's one of the interesting questions we will take up in this course. In a few weeks, you'll know the answer.

1.2.3. Summary

In this lesson, you learned how to:

Learning Objective CRD-2.B: Explain how a program or code segment functions.

• A program needs to work for a variety of inputs and situations.

• The behavior of a program is how a program functions during execution and is often described by how a user interacts with it.

• A program can be described broadly by what it does, or in more detail by both what the program does and how the program statements accomplish this function.

Learning Objective CRD-2.C: Identify input(s) to a program.

• Program input is data sent to a computer for processing by a program. Input can come in a variety of forms, such as tactile, audio, visual, or text.

• An event is associated with an action and supplies input data to a program.

• Events can be generated when a key is pressed, a mouse is clicked, a program is started, or by any other defined action that affects the flow of execution.

• Inputs usually affect the output produced by a program.

• In event-driven programming, program statements are executed when triggered rather than through the sequential flow of control.

• Input can come from a user or other programs.

Learning Objective CRD-2.D: Identify output(s) produced by a program.

• Program output is any data sent from a program to a device. Program output can come in a variety of forms, such as tactile, audio, visual, or text.

• Program output is usually based on a program's input or prior state (e.g., internal values).

Technical Terminology

Here is a table of the technical terms that were introduced in this lesson and that will be used throughout the course. You will see tables such as this in many of the lessons.

algorithm control structure sequence	selection repetition iteration