Assign a Name to a Turtle¶
Use assignment to name objects like turtles and screens.
Ask turtle objects to perform actions.
Introduce the concept of a procedure, which does some action, but doesn’t return a value.
Introduce some turtle procedures like
Demonstrate that you can create more than one object of a type.
Demonstrate that using the right object at the right time, in order, is critical to success.
Names can be more than numbers and strings. They can also be turtles or “screens” (a space on the page where a turtle can draw). You can also call things like turtles and screens objects. Objects in programming are the things that do the action in a program. Objects can have attributes and behavior. An example of an attribute is a position and an example of a behavior is the ability to go forward.
We have seen the example below once before. It allows us to use the
turtle library, creates a
space for a turtle object to draw on, creates a
turtle object and names it
alex to go forward by 150 pixels, asks
alex to turn left 90 degrees, and asks
alex to go forward 75 pixels.
What does a left turn of 90 mean?¶
When we ask a turtle to turn left, it will turn left based on the direction it is currently heading. A turtle object keeps track of its heading (direction it is facing). Use the figure below to help you understand how much the turtle will turn if asked to turn left 90 degrees and it is currently heading east (0 degrees).
Mixed up programs
The following problem has a Help Me button. You can click on the Help Me button after you have made at least 3 full and distinct attempts to solve the problem to make the problem easier.