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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 l.jpg

Logo Lesson 1

TBE 540-40

Fall 2004

Farah Fisher


What is logo l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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.


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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 l.jpg
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 l.jpg

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 l.jpg

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 l.jpg
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 l.jpg

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 l.jpg
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 l.jpg

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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg

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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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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