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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.

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Presentation on theme: "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."— Presentation transcript:

1 Logo Lesson 1 TBE Fall 2004 Farah Fisher

2 What is Logo?  A programming language (instructions to the computer to perform a task)  Created at MIT during a study of artificial intelligence (see foundation/logo/index.html) foundation/logo/index.htmlhttp://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!

3 What is Logo?  When Logo is used to create pictures, commands are given to a “robot turtle”.  Some samples of the “turtle” shape:

4 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

5 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)

6 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.

7 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?

8 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

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

10 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

11 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 90 FD 50 RT 90  Notice that the number of repeats comes first, with the commands to be repeated inside square brackets.

12 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.

13 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]

14 More about REPEAT REPEAT 3 [FD 30 RT 120] REPEAT 8 [FD 30 LT 45] REPEAT 6 [FD 30 LT 60] REPEAT 5 [FD 30 LT 72]

15 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.

16 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.

17 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.

18 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.

19 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]

20 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.

21 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

22 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):

23 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.)

24 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.

25 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!

26 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?

27 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?

28 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 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]

29 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 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]

30 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

31 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}

32 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?

33 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!

34 Time to Try Logo  Use the class CD-ROM to start Logo or download it from the website at  You should see two windows - one for commands and one to show the drawing. FD 50 RT 90 FD 25

35 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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