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CS 106, Winter 2009Class 17, Section 4

Slides by: Dr. Cynthia A. Brown, cbrown@cs.pdx.eduInstructor section 4: Dr. Herbert G. Mayer, herb@cs.pdx.edu

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Degrees of Learning

• We talk about “learning” something, but actually there are degrees of learning.

• These were explained in a classification system, called “Bloom’s taxonomy”

• There are six major categories, each dependent on the previous one

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Bloom’s Taxonomy (1)

• Knowledge: Recall data or information.– Examples: Recite a policy. Quote prices from memory to a customer.

Knows the safety rules.– Key Words: defines, describes, identifies, knows, labels, lists, matches,

names, outlines, recalls, recognizes, reproduces, selects, states.

• Comprehension: Understand the meaning, translation, interpolation, and interpretation of instructions and problems. State a problem in one's own words.– Examples: Rewrites the principles of test writing. Explain in one’s own

words the steps for performing a complex task. Translates an equation into a computer spreadsheet.

– Key Words: comprehends, converts, defends, distinguishes, estimates, explains, extends, generalizes, gives examples, infers, interprets, paraphrases, predicts, rewrites, summarizes, translates.

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Bloom’s taxonomy (2)• Application: Use a concept in a new situation or unprompted use of an

abstraction. Applies what was learned in the classroom into novel situations in the work place.– Examples: Use a manual to calculate an employeeís vacation time. Apply laws of statistics

to evaluate the reliability of a written test.– Key Words: applies, changes, computes, constructs, demonstrates, discovers,

manipulates, modifies, operates, predicts, prepares, produces, relates, shows, solves, uses.

• Analysis: Separates material or concepts into component parts so that its organizational structure may be understood. Distinguishes between facts and inferences. – Examples: Troubleshoot a piece of equipment by using logical deduction. Recognize

logical fallacies in reasoning. Gathers information from a department and selects the required tasks for training.

– Key Words: analyzes, breaks down, compares, contrasts, diagrams, deconstructs, differentiates, discriminates, distinguishes, identifies, illustrates, infers, outlines, relates, selects, separates.

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Bloom’s taxonomy (3)• Synthesis: Builds a structure or pattern from diverse elements. Put

parts together to form a whole, with emphasis on creating a new meaning or structure.– Examples: Write a company operations or process manual. Design a machine to perform a

specific task. Integrates training from several sources to solve a problem. Revises and process to improve the outcome.

– Key Words: categorizes, combines, compiles, composes, creates, devises, designs, explains, generates, modifies, organizes, plans, rearranges, reconstructs, relates, reorganizes, revises, rewrites, summarizes, tells, writes.

• Evaluation: Make judgments about the value of ideas or materials.

– Examples: Select the most effective solution. Hire the most qualified candidate. Explain and justify a new budget.

– Key Words: appraises, compares, concludes, contrasts, criticizes, critiques, defends, describes, discriminates, evaluates, explains, interprets, justifies, relates, summarizes, supports.

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Bloom’s Taxonomy Categories

• Knowledge• Comprehension• Application• Analysis• Synthesis• Evaluation

• To be able to actually use knowledge, you have to get to at least the Application stage.

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Example: Grammar

• Knowledge: I am able to tell you some rules of grammar, but when I actually write something, it might still be grammatically incorrect

• Application: I can use the rules of grammar to write grammatically

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Business Processes

• Having good processes is important in many business situations– Think about how orders are processed at

McDonald’s. It’s the same at every store all over the world, and they hardly ever make a mistake.

– How is a loan application processed at a bank? Some ill-advised changes led to problems!

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Our Goal: Process Design

• We want you to actually design a business process

• This means you can apply your knowledge to carry out the steps:– Develop requirements (use cases)– Develop tests based on the requirements– Design the user interface and identify the objects– Design the actual process using typical

components

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Process Components

• Event-driven structure• A process may involve:– Sequential steps– Encapsulation of sub-processes (procedures and

functions)– Conditional steps (various types of ifs)– Repetition (various types of loops)

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Learning to Apply Loops

• Assignment 6 is about learning to apply loops• Instead of having you write a program, it has

you experiment with loops and observe their behavior

• You will write one small loop

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Loop Review

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For loop

• Repetitions are called loops in VB• A For loop is used when we can determine the

number of repetitions before starting the loopnum = Cint(txtInput.Text)strNum = txtInput.TextlstMult.Items.Clear()Forj = I To 12lstMult.Items.Add(strNum&“ x “ &CStr(j) &“ = “ & _CStr(num * j))Next

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For loop version 2

• Let’s modify the previous example so it prints a multiplication table up to N * N, instead of going to 12.

num = Cint(txtInput.Text)strNum = txtInput.TextlstMult.Items.Clear()Forj = I To num ‘limits can be numbers, variables or expressionslstMult.Items.Add(strNum&“ x “ &CStr(j) &“ = “ & _CStr(num * j))Next

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For Loop Syntax

ForcVar = sValToeValstatementsNext

Here cVar is the control variable, sVal is the start value for cVar, and eVal is the end value for cVar

cVar>eVal?

Execute loop statements

Increment cVar

yes

no

cVar = sVal

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The Do-While Concept

• Sometimes we can’t tell in advance how many times a loop will need to execute

• Or, it might just be clearer to use a logic that checks as we go along

• In that case we can use a Do loop instead of a For loop

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Do-while example

• Let’s try the same program we did with the For loop, but this time with a Do-While loop

num = Cint(txtInput.Text)strNum = txtInput.TextlstMult.Items.Clear()j = 1Do While j<= 12lstMult.Items.Add(strNum&“ x “ &CStr(j) &“ = “ & _CStr(num * j))j = j + 1 ‘what would happen if I forgot this line?Loop

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Do-while example

• Here’s the n by n version

num = Cint(txtInput.Text)strNum = txtInput.TextlstMult.Items.Clear()j = 1Do While j<= num ‘note the upper bound is now a variablelstMult.Items.Add(strNum&“ x “ &CStr(j) &“ = “ & _CStr(num * j))j = j + 1 Loop

• What happens if num = 0?

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Do Loop Syntax (While)

Do While conditionstatement(s)Loop

(Loop statements may never be done.)

Condition true?

Execute statements within the loop.

Execute statementsthat follow the loop.

No

Yes

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Do Loop Syntax (Until)

Dostatement(s)Loop Until condition

(Loop statements are always done at least once.)

Condition true?

Execute statements within the loop.

Execute statementsthat follow the loop.

No

Yes

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BREAK

10 minutes

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Nested Loops

• Remember how if statements can be “nested”: you can have an if inside another if

• We can also put whatever we want inside a loop, including another loop

• If we do this, the inner loop is executed completely, for all of its repetitions, each time the outer loop is executed once.

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Example: Complete Multiplication Table

Dim j, k As IntegerDim tableLine As StringFor j = 1 To 12

tableLine = “”For k = 1 To 12

tableLine = tableLine & CStr( j ) & “ x “ _& CStr( k ) & “ = “ & CStr( j * k ) & “ “

Next ‘klstMult.Items.Add( tableLine )

Next ‘j

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Recursion

• Recursion is a powerful technique for thinking about a process

• It can be used to simulate a loop, or for many other kinds of applications

• In recursion, a function or procedure calls itself• Obviously, there is a danger of an infinite regress,

so there has to be a test for stopping it, and something (usually a parameter) must change between calls