NOVEL CURRICULA  AND TOOLS FOR JAVA

IN CS1 COURSES

Glenn D. BlankComputer Science & Engineering Department

Lehigh University, Bethlehem, PA, USA

With support from the National Science Foundation (Grants No. EIA-0087977 and 0624553)

and the Pennsylvania Infrastructure Technology Alliance

Outline A “design-first” approach to the first CS

course Elaboration of “objects-first” approach Multimedia introducing classes, methods &

attributes Eclipse, LehighUML and DrJava tools

Intelligent Tutoring System (ITS) support Evaluation results Widening the pipeline of women and

minorities from middle school to college

Who’s on first?From syntax to objects to design

Ongoing debate about how to introduce object-oriented concepts to novices

Syntax-driven approach (traditional): Typically starts with “Hello, World” then arithmetic

Objects-first approach Starts by manipulating classes, objects and methods But objects-first textbooks still tend to emphasize coding

and syntax rather than “object think” Design-first approach:

First learn how to solve a problem Novices need to see the big picture:

Software development is more than just coding It’s understanding a customer’s problem

and designing a solution

So, what is “design-first”? Students learn object-oriented concepts

early and apply them from the start Given a problem description, students

learn how to design a UML class diagram within first two weeks of a CS1 course

Using modern software development tools Eclipse with DrJava & LehighUML

LehighUML plug-in

DrJava plugin

Eclipse IDE

Four easy lessons

1. “Big picture of software development” Compare building a house to constructing software Discussion and small group work with handout (an hour)

2. Objects and classes Multimedia lesson (preferably in lab, 90 minutes)

3. From problem description to class diagram Step by step procedure based on OO design principles

4. Design a class, with ITS help Lab exercise, takes about 90 minutes

Objects and classes: multimedia lesson Implemented in Flash with graphics, animation & sound Core concepts of classes, methods and attributes Eclipse IDE

set up for novices

LehighUML and DrJava

Manipulateconstructorsand methodsfor shapes

Create amethod thatdraws ascene

Demo the multimedia

Plug in a head set for sound Start Microsoft Internet Explorer http://cimel.cse.lehigh.edu login: evb209 password: beit*8 The Universal Computer – breadth-first intro

to Computer Science (with a textbook: see www.cse.lehigh.edu/~glennb/um)

Design First with Java: Objects and Classes

From problem description to class diagram (in eight steps)1. Read the problem description at least twice. Ask questions about anything you don’t understand or needs more explanation. (The students receive a problem description and ask questions.)

2. Put an ‘S’ next to each subject, a ‘V’ next to each verb and an ‘O’ next to each object.

The ATM verifies whether the customer's card number and his her PIN are correct. S V O Oher PIN (a number) are correct. If it is, then the customer can check the account balance, O S V O deposit cash, and withdraw cash. Checking the balance simply displays the account balance. V O V O S O V ODepositing asks the customer to enter the amount, then updates the account balance. S V O O V O Withdraw cash asks the customer for the amount to withdraw; if the account has enough cash, S O V O O V S V Othe account balance is updated. The ATM prints the customer’s account balance on a receipt. O V S V O O

Analyze subjects and objects

The ATM verifies whether the customer's card number and PIN are correct. S V O O OIf it is, then the customer can check the account balance, deposit cash, and withdraw cash. S V O V O V O Checking the balance simply displays the account balance. S O V ODepositing asks the customer to enter the amount, then updates the account balance. S V O V O V O Withdraw cash asks the customer for the amount to withdraw; if the account has enough cash, S O V O O V S V Othe account balance is updated. The ATM prints the customer’s account balance on a receipt. O V S V O O

3. Analyze each subject and object as follows: Does it represent a person performing an action? Then is an actor, ‘R’. Is it also a verb (such as ‘deposit’)? Then it may be a method, ‘M’. Does a subject take a simple value, such as ‘color’ (string) or ‘money’ (number)?

Then it is probably an attribute, ‘A’. Which remaining unmarked noun occurs most frequently? Make it ‘C’ for class. In Eclipse, draw a class for your first class.

R

R

M

M

A A

A

A

A

A A

A

A A

A A

A A

A

C

C

R

M

R

Analyze methods and attributes

4. If a verb has a non-actor object it’s a method, M5. Distinguish attributes, A, and parameters, P: If it doesn’t distinguish instances of a class or store information

about objects, it’s probably a parameter, not an attribute Add attributes to a class in the UML class diagram Add methods in the class diagram While adding methods, include the parameters See the return type of your methods:

“get” methods take the type of the attribute returned “set” methods take “void” return type compute methods take the type of the computed value Methods that answer true/false questions take boolean type

Constructor(s)

Any more classes?

6. If any remaining classes has no attributes, it’s probably an attribute of another class

7. Otherwise, add another class to the diagram and go back to step 4 (analyze its methods and attributes)

8. Draw association links between the classes

Check your design to make sure it makes sense!

Eclipse setup for novices Eclipse

Open source, so it’s free! Widely used in academia and industry Students learn one IDE; learn features as needed Good error messages and syntax support Caveat: it’s complicated for novices to set up and learn! Multimedia explains how to set it up and get started using it

DrJava plug-in (www.drjava.org) Interprets Java expressions from compiled code Supports test-driven programming

LehighUML plug-in Students enter class diagram Generates code stubs for class automatically Instead of syntax, students focus on design

Eclipse for novices demo

Eclipse: incremental compiler, debugger, plugins DrJava interprets any Java expression from byte-

compiled code Supports test-driven development of methods

LehighUML creates UML class diagrams With or without intelligent tutoring support Right click on class diagram > Properties for details

Check it out: Login as cscc1, cscc2, … cscc15 Login connects to a server which provides

intelligent tutoring system support

Lab exercise: Design a movie ticket vending machine

The movie ticket machine displays the movie title, displays the show time (e.g. “2006-11-16 7:00pm”), and displays the price of a ticket (e.g. 8.50). A customer enters money (e.g. 20.50) into the machine. The machine displays the customer’s balance (e.g. 20.50). The customer enters the number of tickets (e.g. 1) into the machine. The machine prints the tickets, and returns the customer’s balance (e.g. 12.00). Print tickets also tracks the number of available seats in the theater so it can tell the customer when the available seats are sold out.

DesignFirst-ITS architecture

Expert Evaluator – Sally Moritz

Interprets each step of a student’s solution Matches student step with pieces of expert solutions Applies concepts in Curriculum Information Network Produces info packets for rest of ITS

Allows variations from expert solutions Matches synonyms and abbreviations An attribute in expert solution can also be defined as a class

(e.g. class “Time” with TicketMachine’s attribute showTime) “Unknown” elements (can’t be matched to anything in

problem description or solution) are the most problematic Pedagogical advisor encourages student to use terms related

to the problem description

Feedback when student enters an unknown class

Expert Solution Generator

Teacher’s problem description Suggested solution

Expert Solution Generator

Generates multiple possible “expert” solutions Analyzes natural language problem description Algorithm similar to what we now teach novices Uses MontyLingua NL parser to tag parts of speech

Student Model – Fang Wei

Challenges: OO design requires understanding

of concepts (not just procedural rules) E.g., class, method, attribute, data type, etc. Concepts depend on prerequisites E.g., attribute vs. parameter attribute, parameter

Student works in an open-ended environment LehighUML plug-in provides some scaffolding Students learn how to apply concepts in design

Limited time for updating the Student Model EE+SM+PA must respond in real student time Bayesian networks can take exponential time

actor

actor_object

object

object_class

class

class_attribute

attribute

attribute_constructor

constructor

doubleint

numeric datatype

datatype

string

datatype_variable

variable

variable_parameter

parameter

variable_returntype

returntype

pass in only

class_method

method

method_constructor

class_constructor

object_constructor

method_parameter

variable_attribute

object_attribute

object_method

double_int

int_string

double_string

method_returntype

datatype_returntype

attribute_method

attribute_parameter

actor_method

A is prerequisite of B A B

Curriculum Information Network of concepts

Two kinds of concepts (KU)

Unique concept, such as attribute or parameter Relationship concept, such as attribute_parameter Relationships emerge because of student

confusions between concepts E.g., student defines movieTitle as a parameter

when he has already defined movieTitle as an attribute

Two kinds of concepts (KU)

Unique concept, such as attribute or parameter Relationship concept, such as attribute_parameter Relationships emerge because of student

confusions between concepts E.g., student defines movieTitle as a parameter

when he has already defined movieTitle as an attribute

Prerequisite relationships

Prerequisite is relationship between concepts or knowledge units:

The concepts a learner needs to understand before understanding a concept

E.g., one needs to under int and double in order to understand numeric_datatype

Relationship concepts are prerequisites of unique concepts and vice versa

E.g., class_constructor -> constructor Understanding constructor doesn’t imply

understanding of class, just how to define a constructor for a class

……

au

ku

d-prereq(ku)1 d-prereq(ku)2d-prereq(ku)N

Atomic Bayesian Network (ABN)

A directed graph composed of one edge(ku,au)(concept or knowledge unit impliesaction unit or step in student solution)

multiple edges(direct-prerequisite(ku),ku)

Noisy-andgeneralizeslogical-and Students must understand all direct

prerequisites of the concept ku in order to understand ku

Since unique concepts (attribute, parameter) and relationship concepts(how to distinguish between attribute and parameter) are not transitive,ABN only needs to consider direct-prerequisites

Three-level architecture

• CM recognizes a student’s cognitive strategies (e.g., hacking vs. analogy)

• HM tracks history of student’s conceptual knowledge

•PDM simulates student’s conceptual knowledge

Evaluation using 240 simulated students:

• Problem Domain Layer is 94% accurate• where accuracy means that given probabilities of a simulated student’s understanding of relevant concepts, SM correctly predicts

student’s solution step• Adding Historical Model increases accuracy to 98.5%

Atomic Dynamic Bayesian Networks

ADBNs extend ABNs to account for knowledge states over successive time slices Each time slice is an ABN connected to next ABN

Evaluated of student model 71 college and high school students in CS1 courses

Compared diagnosed knowledge state for each student with the ones reflected from posttest. Average correct diagnostic rate is 81.8% Improves to 89.5% by adding multimedia observations Average response time after a student enters the solution

step is 0.63 seconds, comfortably real time for the students

Pedagogical Advisor with Learning StylesShahida Parvez

What is an individual learning style?The way a learner perceives and interacts with an environment.Some people like information in the form of pictures / images,

while others like it in written form. Some like to work alone while others like to work in groups. Some prefer concept and theory while others like facts

and concrete experience.

Visual Learner

Auditory Active Learner Learner

Pedagogical Advisor architecture

Felder-Silverman learning style survey

http://designfirstui.cse.lehigh.edu:8080/servlets-examples/servlet/LearningStyle

Survey has been validated 44 questions determine learning styles along

8 dimensions

Feedback for a visual / global / sensing / reflective learner

Feedback for a verbal / global / sensing / reflective learner

Feedback for a visual / sequential / intuitive

Evaluation 49 CS1 students completed four lesson introduction

to object-oriented design After multimedia, students took a multiple choice test on

object-oriented concepts Out of 31 questions, mean of 5.5 errors Confirms previous pre-test/post-test results demonstrating

effectiveness of multimedia (Blank et all 2003, 2005) All students completed TicketMachine design

Average graded score of 96.9/100 (1 point per error) Out of 31 questions, mean of 2.3 errors Lab exercise with ITS help had a significant effect

Using paired-samples t test, the T value is 10.2111, p<.001

Standalone DrJava and LehighUML

Eclipse is popular for large-scale software development, but has a steep learning curve

DrJava (BlueJ, etc.) more suitable for novices? DrJava.exe (from www.drjava.org) New: standalone version of LehighUML

Widening the pipeline

The pipeline for women and minorities entering computer science (CS) and information technology (IT) is shrinking, at a time when the projected demand for IT professionals is growing Camp, 1997, 1999, Cohoon, 2002

“We must take direct action to attract and retain more women to computing at all points in the pipeline (i.e., K-12, undergraduate, graduate, faculty and industry).” Camp 1999

LV (Lehigh Valley) STEMwww.lehigh.edu/stem An NSF-sponsored GK-12 project Faculty and Graduate Fellows lead outreach teams Work with K-12 teachers to develop new curricula

Martian landscape with remotely controlled robot “rovers” created in the basement of an Allentown middle school (now a NASA Explorer school)

Flash introduced in a Bethlehem middle school Design-first curriculum in an Allentown high school

NSF program manager has indicated likely recommendation for a continuing GK-12 project New project also feature smaller Outreach supplements

for grads or undergrads to implement curricula developed by Graduate Fellow teams

Launch-IT (NSF ITEST) www.lehigh.edu/launchit

Build on success of LV STEM and S.T.A.R. Academies Promote academic achievement for at-risk middle & high school

students in the Lehigh Valley 98% of S.T.A.R. students go to college (now in 18th year) Saturdays (once a month) and summer (three weeks) Corporate partners, regional colleges & schools, and parents

Focus on Information Technology (IT) Connect & widen pipeline laid that STEM laid in schools Self-directed multimedia, intelligent tutoring, and one-on-one

mentoring by college undergraduate and graduate students Three teams led by IT faculty and Graduate Fellows

6th and 7th graders: science, math and IT ‘missions’ using remotely controlled robots in a simulated Martian landscape

8th and 9th graders: create web-based juke box or iPod™ as an interactive, animated web site using Flash™

10th through 12th graders: learn Java “design first” with goal of getting AP Java college credit

Thank you!

Questions?

glennblank@gmail.comwww.cse.lehigh.edu/~glennbdesignfirst.cse.lehigh.edu