Logo Programming What is LOGO l l LOGO

Logo Programming

What is LOGO? l l LOGO is one of a number of computer languages to have been developed in the field of Artificial Intelligence. LOGO was developed at the Massachusetts Institute of Technology in the late 1960's as part of a research project to create a language for the teaching of mathematical ideas to children through computer programming. It was intended to be easy to learn, easy to use, easy to read, but also powerful, and therefore able to cope with complex activities. LOGO was evolved by a team including Wallace Feurzeig (who suggested the name LOGO), Cynthia Solomon and the man who is now the most well-known LOGO figure, Seymour Papert.

Different versions l l MSW Logo HKU Logo PC Logo Star. Logo (used for modeling) HKU Logo Vs MSW Logo

HOW DOES LOGO WORK? l l l Logo programs are built up through the use of procedures. A computer program in LOGO is just a collection of procedures which achieve a particular objective. The work TO is used when creating ('defining') procedures; this is to emphasize the way we can think of procedures as being like verbs.

LOGO and THINKING l Proponents of LOGO argue that LOGO programming can be seen as a direct analogy of the thinking process itself. l The similarity between the building up of LOGO programs and the building up of thought-structures is clear. The evolution of a LOGO program by developing and testing simple procedures, then incorporation them in more complicated ones can to some extent parallel the process of thinking. l For Papert, this similarity between LOGO-work and 'thought-work' is what makes LOGO not just a programming language but a 'tool to think with'. l Learning, at any level, proceeds by a process of trial and error.

LOGO and THINKING l The unexpected response is seen as a positive step in the right direction, and the learner is encouraged to think about why the unexpected result occurred. Unexpected results are therefore seen as useful stages in the learning process. l 'Debugging', is considered to be an essential part of the learning process, by which conceptual structures are tested and altered until found acceptable. l 'Bugs' are not seen as 'wrong answers' but as unexpected outcomes which should stimulate thinking and lead to the mastery of ideas that comes from an understanding of how to use them successfully.

LOGO and SCHOOLS LOGO is often suggested as ' ideal computer language for children' ; and most of the current interest in it comes from educational practitioners. What does LOGO offer schools in particular?

l l The main justification for LOGO-use in schools arises from the nature of the LOGO learning experience. Exploration and discovery are generally accepted as essential parts of the experience which the schools can offer. LOGO also offers a ready avenue into familarisation with and general use of the computer LOGO offers an introduction to computer programming which is highly structured and encourages 'top-down' programming. The importance of 'debugging' in learning has been mentioned above.

l l l It is a common observation of those who have used LOGO in the classroom, that LOGO is enjoyable. The fact that learning is enjoyable is not trivial, for enjoyment in learning is a source of motivation and of concentration. LOGO is most effectively used with groups, and when so used enables the learning benefits of group activity to be obtained. Because of the range of 'microworlds' which it can support. LOGO can be used to allow children to explore various and different elements of the curriculum, while maintaining a unity of good thinking practice.

Logo as a Programming Language l l l Logo is procedural Logo is interactive Logo is recursive Logo has list processing Logo is not typed Logo is extensible

Logo as a Learning Language l l l Logo, though, was developed as a learning language, not for a specific branch of mathematics, but for problem-solving behavior. Logo is 'tuned' for interesting applications. Logo is user-friendly. Logo has no threshold and ceiling. Logo is for learning.

What facilities Does LOGO offer? l l l l Different sets of LOGO facilities can place the user in different 'micro-worlds' which can become environments for exploration and discovery, and thus environments for learning. Some micro-worlds : the 'turtle world' of the plane geometry the 'music world' the 'dynaturtle world' of movement in outer space; database possibilities; robotics and control possibilities; facilities for poetry and creative writing etc

Learning Styles l l l Planner l likes to build structured programs from the top level down or from the bottom level up, but always from a coherent formulated plan. macro-explorer l likes to mess about with subprocedures or building blocks to arrive at a product, rather than starting out with a specific goal. micro-explorer l explore their environment on a microlevel before they can establish patterns of planning or directed exploration.

As Logo is a popular programming language, there exists different versions of Logo. In your school, you may find the following versions: l l l HKU Logo (CGA version) HKU Logo (VGA version) PC Logo for DOS PC Logo for Windows MSW Logo

Some differences ….

Working environment of HKU Logo. Graphic Window The Upper part is the graphic window while the lower part is the text window. You can type the commands in the text window to instruct the turtle Text Window

MSW LOGO The turtle is sitting at the centre of its playground. Down below the playground is the Commander window. To instruct the turtle, you simply type the commands in the Input Box and click on the execute button (or just press the ENTER key) to execute them Menu Bar Turtle's Playground The turtle Commander Window Input Box Output/Command-Recall List Box Command buttons

Learn Turtle’s ABC (for HKU Logo users) Press the Enter key at the end of each instruction. ? FD 50 Press the spacebar to add a space here. ? FD 50 ? RT 90 ? FD 40 ? LT 90 ? BK 100 Add these instructions and remember to press the Enter key at the end of each instruction.

Learn Turtle’s ABC Press the spacebar to add a space here. (for MSW Logo users) Press the Enter key at the end of each instruction.

First procedure for HKU Logo user

The above procedure can be used to draw a square. If you want to use the procedure, you only need to type the name of the procedure after the prompt ‘? ’, for example, ? SQUARE and then a square will be drawn.

First procedure for MSW Logo user Type to square in the input box In MSW Logo, the commands can be typed in upper or lower cases.

You will see a dialog box which let you input the Logo commands. Type repeat 4[fd 100 rt 90] and press Enter.

Input end to indicate that you have completed procedure. Remember to press Enter or click the OK button

The commander box will tell you that your procedure has been defined Logo tells you that the procedure called SQUARE has been defined.

The above procedure can be used to draw a square. If you want to use the procedure, you only need to type the name of the procedure in the input box.

A square will be drawn on screen.

Group Activity Compare and contrast HKU LOGO with MSW LOGO Try to compare and contrast these two versions of LOGO in the following aspects: l l l Working environment Basic Movements Procedures Workspace and file management Flow control Project Handling

Designing a programming project

How to tackle a Logo Project Defining the problem Completing the project and sharing your work with others Setting up appropriate goals Debugging and Revising the project Creating a Working Draft

Some hints for developing Logo projects: l l Top-down analysis Modular approach State-transparent Meaningful variable names and procedure names

Project example:

Defining the problem I want to ask the turtle to build a house.

Setting up appropriate goals My dream house should have a roof, a door, walls and windows.

Creating a working draft

House Roof Triangle Wall face Rectangle 1 Door Rectangle 2 Window Rectangle 3

TO TRIANGLE REPEAT 3 [FD 80 RT 120] END TO ROOF RT 30 TRIANGLE LT 30 END

TO WALLFACE RT 90 FD DOOR RT 90 BK PU FD 80 WINDOW 1 PU BK 80 END 25 LT 90 RT 90 FD 10 LT 90 PD LT 90 FD 10 RT 90 PD RT 90 FD 50 LT 90 PD LT 90 FD 50 RT 90 PD

The house can be built now! TO HOUSE WALL FD 100 ROOF BK 100 END

Debugging and Revising : LENGTH*30/80 : LENGTH*20/80 : HEIGHT*10/100 : HEIGHT*60/100

Completing the project and sharing your work with others House Roof Triangle Wall face Door Rectangle Window Rectangle TO TRIANGLE : LENGTH REPEAT 3[FD : LENGTH RT 120] END TO RECTANGLE : H : L REPEAT 2 [FD : H RT 90 FD : L RT 90] END

To be a Town Planner

How to design an IT task for learning Logo? Activity Try to draft a learning task for a selected Logo topic.