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Logo Lesson 1. TBE 540-40 Fall 2004 Farah Fisher. What is Logo?. A programming language (instructions to the computer to perform a task) Created at MIT during a study of artificial intelligence (see http://el.media.mit.edu/logo-foundation/logo/index.html )

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logo lesson 1

Logo Lesson 1

TBE 540-40

Fall 2004

Farah Fisher

what is logo
What is Logo?
  • A programming language (instructions to the computer to perform a task)
  • Created at MIT during a study of artificial intelligence (see http://el.media.mit.edu/logo-foundation/logo/index.html)
  • Can be used by virtually any student - from young children through engineering students
  • Can be used to create pictures, display text, or perform calculations. Some versions can even make music!
what is logo3
What is Logo?
  • When Logo is used to create pictures, commands are given to a “robot turtle”.
  • Some samples of the “turtle” shape:
what does logo look like
What does Logo look like?
  • The simplest form of Logo uses movement commands to control the “robot turtle”.
  • Sample commands:
    • FD (or FORWARD) moves the turtle forward
    • BK (or BACK) moves the turtle backwards
    • RT (or RIGHT) turns the turtle to the right
    • LT (or LEFT) turns the turtle to the left
what does logo look like5
What does Logo look like?
  • Each movement command (FD, BK, RT, LT) needs more information.
  • FD and BK both require a number, which indicates the “turtle steps” to move (steps are very small).
  • RT and LT both require the number of degrees in the turn.
  • Examples (notice the space after the command):
    • FD 50 (move forward 50 turtle steps)
    • LT 90 (turn left 90 degrees)
what does logo look like6
What does Logo look like?
  • As the turtle moves, it leaves a “trail” on the screen.
  • These “trails” make shapes.
  • Imagine for a moment that you are walking around the bases of a baseball diamond, about 30 steps on each side. Assume that you are walking forward from base to base. Are you turning left or right?
  • Go to the next slide when you finish.
what does logo look like7
What does Logo look like?
  • In walking around the baseball diamond in your imagination, you probably followed these steps (written as they would be in Logo):
    • FD 30 (home to 1st base)
    • LT 90 (turn toward 2nd base)
    • FD 30 (1st base to 2nd base)
    • LT 90 (turn toward 3rd base)
    • FD 30 (2nd base to 3rd base)
    • LT 90 (turn toward home)
    • FD 30 (3rd base to home)
  • Imagine that you were dragging a paint brush when you walked. What shape would you have drawn?
what does logo look like8
What does Logo look like?
  • The commands below would make a square! (turtle shown at the end)

FD 30

LT 90

FD 30

LT 90

FD 30

LT 90

FD 30

what shapes would these make
SHAPE 1

FD 30

RT 90

FD 60

SHAPE 3

FD 50

LT 60

FD 50

SHAPE 2

RT 90

FD 50

LT 90

FD 50

SHAPE 4

FD 100

RT 45

FD 50

What shapes would these make?

Try these with pencil and paper. Click to check your answers.

what shapes would these make10
SHAPE 1

FD 30

RT 90

FD 60

SHAPE 3

FD 50

LT 60

FD 50

SHAPE 2

RT 90

FD 50

LT 90

FD 50

SHAPE 4

FD 100

RT 45

FD 50

What shapes would these make?
the repeat command
The REPEAT Command
  • When you “walked around the bases”, you may have noticed that the Logo commands were repeated.
  • The REPEAT command is used as a shortcut in place of writing out repeated commands.
  • Example: REPEAT 2 [FD 50 RT 90] is the equivalent of FD 50 RT 90FD 50 RT 90
  • Notice that the number of repeats comes first, with the commands to be repeated inside square brackets.
repeat example
To make a SQUARE

FD 30

LT 90

FD 30

LT 90

FD 30

LT 90

FD 30

OR…to make a SQUARE

REPEAT 4 [FD 30 LT 90]

This version actually adds another LT 90 to the list, but does not change the basic shape.

REPEAT Example
more about repeat
More about REPEAT
  • You have seen that REPEAT 4 [FD 30 LT 90] makes a square. Guess the shapes made by the REPEAT commands below. Click to see if you were right.

REPEAT 3 [FD 30 LT 120]

REPEAT 6 [FD 30 LT 60]

REPEAT 8 [FD 30 LT 45]

REPEAT 5 [FD 30 LT 72]

more about repeat14
REPEAT 3 [FD 30 RT 120]

REPEAT 8 [FD 30 LT 45]

REPEAT 6 [FD 30 LT 60]

REPEAT 5 [FD 30 LT 72]

More about REPEAT
did you notice a pattern
Did you notice a pattern?
  • The number after REPEAT is the number of sides.
  • Examine the number of repeats and the number of degrees. Try multiplying them together. Example: 4 (sides) x 90 (turn)
  • The sides x degrees should always be the same number in the samples you tried.
  • Could you use this information to make a 10-sided figure? Click for a possible answer.
did you notice a pattern16
Did you notice a pattern?
  • REPEAT 10 [FD 30 LT 36] should make a 10-sided figure.
  • Why? Look at the “total turtle turns” below:

REPEAT 3 [FD 30 LT 120] 3 x 120 = 360

REPEAT 6 [FD 30 LT 60] 6 x 60 = 360

REPEAT 8 [FD 30 LT 45] 8 x 45 = 360

REPEAT 5 [FD 30 LT 72] 5 x 72 = 360

REPEAT 10 [FD 30 LT 36] 10 x 36 = 360

  • When the turtle makes a closed figure (no breaks in the sides), the total turns add up to 360 degrees.
logo and critical thinking
Logo and Critical Thinking
  • You have just seen an example of the use of Logo to enhance critical thinking.
  • Your students (and you, too) can be challenged to write the sequential steps needed to make shapes, look for patterns, predict outcomes…all part of critical thinking.
  • Watch for more examples of critical thinking as you learn Logo.
changing things
Changing Things
  • Here is another prediction task for you.
  • You have seen that to make a square, you can use REPEAT 4 [FD 30 LT 90]
  • Do you think the same commands would work if you turned RT instead of LT?
  • How could you make a square larger? What would you have to change?
  • After you have made predictions, go to the next slide.
were you correct
REPEAT 4 [FD 30 LT 90]

REPEAT 4 [FD 30 RT 90]

REPEAT 4 [FD 10 LT 90]

REPEAT 4 [FD 50 LT 90]

Were you correct?
controlling the logo pen
Controlling the Logo “Pen”
  • When the Logo turtle moves, it usually draws with a “pen”.
  • This pen can be “down” (draws a line) or “up” (does not draw a line). If the pen is up, the turtle moves without drawing.
  • The pen can also become an eraser (remove a line already drawn).
  • The pen color abd background can be changed.
pen control commands
Pen Control Commands
  • PU (PENUP) - subsequent movements of the turtle will not leave a line
  • PD (PENDOWN) - subsequent movements of the turtle will leave a line
  • PE (PENERASE) - subsequent movements of the turtle will erase any line it crosses
  • PPT or PP (PENPAINT) - used by some versions of Logo to “undo” PENERASE
logo challenge
Logo Challenge
  • How could you use PU and PD to make a dashed line (like the middle of a road)?
  • Think about this problem for awhile, then click for a possible answer.
  • Try making the pattern below (turtle always starts pointed “up” with the pen down):
logo challenge23
Logo Challenge

Two possible solutions for this shape:

RT 90 FD 25 PU FD 25 PD FD 25 PU FD 25 PD

FD 25 PU FD 25 PD FD 25

Alternate using REPEAT:

RT 90 REPEAT 4 [FD 25 PU FD 25 PD]

OR…You could draw a line and go back over it with an eraser!

(NOTE: Logo commands can be placed on the same line.)

logo color
Logo Color
  • The Logo command to set the pen color is SETPC on most versions of Logo.
  • The Logo commands to set the background color is SETBG on most versions of Logo.
  • Each of these commands must be followed by a number (typically from 0 to 15).
  • The numbers may signify different colors in various version of Logo. You will need to experiment.
  • NOTE: Some versions of Logo use a menu to choose colors.
logo color25
Logo Color
  • Here are some sample commands using color.
  • SETPC 0 (pen will draw in black)
  • SETPC 7 (pen will draw in white - probably)
  • SETBG 3 (screen background will change color)
  • NOTE: If you set the pen color and the background to the same number, you will not see any drawing!
self check for lesson 1
Self-Check for Lesson 1
  • Suppose you enter these commands (with the turtle starting at “home” in the middle of the screen, pointing up): FD 30 RT 90
  • Which shape would appear?
self check for lesson 127
Self-Check for Lesson 1
  • Suppose you enter these commands (with the turtle starting at “home” in the middle of the screen, pointing up): FD 30 RT 90
  • Which shape would appear?
self check for lesson 128
Self-Check for Lesson 1
  • Which of the following is a Logo shortcut for

FD 50 LT 60 FD 50 LT 60 FD 50 LT 60

  • REPEAT 3 (FD 50 LT 60)
  • REPEAT [LT 60 FD 50]
  • REPEAT 3 [FD 50 LT 60]
  • REPEAT [FD 50 LT 60]
self check for lesson 129
Self-Check for Lesson 1
  • Which of the following is a Logo shortcut for

FD 50 LT 60 FD 50 LT 60 FD 50 LT 60

  • REPEAT 3 (FD 50 LT 60)
  • REPEAT [LT 60 FD 50]
  • REPEAT 3 [FD 50 LT 60]
  • REPEAT [FD 50 LT 60]
self check for lesson 130
Self-Check for Lesson 1
  • Which of the following sets of Logo commands will move the turtle 50 steps without drawing?
  • FD 50 PU
  • PU FD 50
  • PE FD 50
self check for lesson 131
Self-Check for Lesson 1
  • Which of the following sets of Logo commands will move the turtle 50 steps without drawing?
  • FD 50 PU
  • PU FD 50 {PENUP starts no drawing} OR
  • PE FD 50 {PENERASE also starts no drawing}
self check for lesson 132
Self-Check for Lesson 1
  • Suppose you type these three Logo commands:
    • SETBG 0 SETPC 0 FD 100
  • What will you see on the screen?
self check for lesson 133
Self-Check for Lesson 1
  • Suppose you type these three Logo commands:
    • SETBG 0 SETPC 0 FD 100
  • What will you see on the screen?

You will see the turtle in a different place, but no line. You have instructed the turtle to draw in black on a black background!

time to try logo
Time to Try Logo
  • Use the class CD-ROM to start Logo or download it from the website at http://www.csudh.edu/fisher/tbe540
  • You should see two windows - one for commands and one to show the drawing.

FD 50

RT 90

FD 25

time to try logo35
Time to Try Logo
  • Try the activities from Hands-On Exercise 1. This is not a graded exercise.
  • Experiment with the Logo commands listed on the handout for Week 1.
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