This section is a quick overview of definitions we’ve already covered, but these are the
definitions you definitely want to get across to the students before starting the lesson. There
are multiple ways you could introduce these definitions to the students, but we encourage
using examples to drive the definitions in.
Algorithm
An algorithm is a sequence of steps to solve a problem or perform a task.
Similar to changing a tire or following a recipe to bake a cake, these actions
take a specific step-by-step processes. In Alice, the algorithms we develop help
to animate the virtual world.
Code
Computer code is how computer users enter instructions for the computer to
understand the step-by-step instructions. Computer scientists use a programming
language to write code. Java, Python, and
C++ are all examples of programming languages. In Alice, this process is
resembled through drag and drop
code blocks allowing users to create programs through visually organizing and
connecting these code blocks.
Method
A method is a group of messages/instructions directed at an object to cause it
to perform a
particular action. In Alice, a method is visually represented as a block that
contains these instructions. For
example, when you want an object to walk, run, or jump, these actions require a
method that tells the object
which action to take.
Object
An object refers to any entity or element that is represented and manipulated
within the virtual
environment (a figure, a ball, a dog). This object is manipulated by the
computer via step-by-step instructions
initiated by the computer user. Objects will behave or act with help from
methods. In Alice, objects also
include non-visual items such as the camera and the light that the user can
apply to their scene.
Parallel
A parallel event is when two actions happen at the same time. In Alice, this
parallel function is
called a do-together block. For example, imagine two characters walking
side-by-side, the user would use a
do-together block to make both characters start walking at the same time.
Sequential
The order in which instructions (lines of code) are executed makes a difference.
If you were
to run straight for one mile, turn left, then run straight for two miles, you
will be in a different spot than
if you run straight for two miles, turn left, then run straight for one mile.
Often, in a computer, code is
executed sequentially, or, in the order in which it appears line-by-line. For
example, in Alice, calling the
jump command followed by the run command will make a character first jump up
and then, second, run.