# Slide 1 - Computer Science at Kent - School of Computing

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```							What do teachers teach in introductory
programming?

Carsten Schulte, Jens Bennedsen
Introduction: Some statistics…

• … on the statistics in the paper

• 28 items in three dimension on four different groups, plus
some other issues ~400 numbers,
each with 3 digits = 1200 digits

• ~20 min presentation time

• 20min*60 sec=1200 -> 1 sec per digit

• Let‟s go ;-)

Schulte, Bennedsen ICER06                                        2
Focus of presentation
–topics–
• Teachers‟ s opinions about what should be taught in CS1
(as an introductory programming course)
•    What to teach besides topics

• Milne and Rowe (2002, p. 55): “inability [of
students] to comprehend what is happening
to their program in memory”
• Lathinen et al (2005, p. 15): “Students also
have problems with understanding that
each instruction is executed in the state
that has been created by the previous
instructions”
• Ragonis and Ben-Ari (2005, p. 214): “[high
school] students find it hard to create a
Flow chart -wikipedia         general picture of the execution”
Schulte, Bennedsen ICER06                                             3
Dimensions of learning programming

Du Boulay

Schulte, Bennedsen ICER06                        4
Notional machine for OO?

1. Interaction with objects
The student can understand simple forms of inter-actions between a
couple of objects, such as method calls and creation of objects. The
student is aware that the results of method calls depend on the identity
and state of the object(s) involved.
2. Interaction on object structures
The student is able to comprehend interaction on more than a couple of
objects, including iteration through object structu-res and nested method
calls. The structure is created and chang-ed explicitly via creations,
3. Interaction on dynamic object structures
The student knows the dynamic nature of object structures, understands
the overall state of the structure and that interaction on the structure or
elements from it can lead to side-effects (e.g. implicit changes in the
structure).
4. Interaction on dynamic polymorphic object
structures
The student takes into account polymorphism in dynamic object
structures and is able to understand the effects of inheritance and late
binding on dynamic changes in the object structure. The student takes
into account side-effects of late binding (different method-
implementations, different actual objects referred to by the same
variable).

Schulte, Bennedsen ICER06                                                                         5
Research Theme

• What do teachers teach in introductory
programming?

• Topics
• Imp. and/or OO

• Didactical perspective
• Research from the eighties
• Role of mental model for oo -> object interaction

• Descriptive (not Explanatory)
Schulte, Bennedsen ICER06                              6
Population

• Participants: teachers at university,
college and high school, worldwide
• are attending educational
workshops or conferences

• are Experts for Teaching

Schulte, Bennedsen ICER06                 7
Responders

Uni-    College High Other Overall
versity         school

Denmark                       5      49       1      3     16.7%
Germany                      16       4      40      6     19.0%
USA                          79      34       4      1     33.9%
Other                        98       4       4      0     30.5%
Overall                                                    100%
56,9%   26,1%   14,1%   2,9%
348
Schulte, Bennedsen ICER06                                          8
OO included

100%

90%

80%

70%

60%
OO-concepts covered
50%
OO-first course
40%

30%

20%

10%

0%
University   College   High school   overall

Schulte, Bennedsen ICER06                                                                        9
Important teaching topics

• Result: list of 28 topics

• Difficulty
• Relevance
• Level

Schulte, Bennedsen ICER06     10
Difficulty of 28 topics, all teachers
Difficulty

4

3.5
3
2.5

2                                                                                All
1.5
1
0.5
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Milne and Rowe: polymorphism, recursion, pointers
Scale: 1 – 5, left side: most;
CC2001: Recursion, AlgEfficiency, Generics,
right side: least                      Adv-Data-Str, Poly are part of CS2

Schulte, Bennedsen ICER06                                                                11
Relevance of 28 topics, all teachers
Relevance

5
4.5
4
3.5
3
2.5                                                                                         All
2
1.5
1
0.5
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We find that today‟s teaching faces the same problems
Scale: 1 – 5, left    Nell Dale: Repetition,             as noticed by [CC2001] and therefore students still
side: most;        Selection,                         associate programming with coding and not with more
right side: least
Information Hiding                 abstract, design-oriented and intellectual challenging
activities.
Schulte, Bennedsen ICER06                                                                              12
Level of 28 topics, all teachers

Level

5
4.5
4
3.5
3
2.5                                                               All
2
1.5
1
0.5
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Scale: 1 – 5, left side:
As before /Relevance): Focus on coding most; right side: least

Schulte, Bennedsen ICER06                                                      13
Correlations between Difficulty, Relevance
and Level

Object communication

4,5
4,0
3,5
3,0
2,5                                              Relevance
2,0                                              Difficulty
1,5
1,0
0,5
0,0
Yes              No

OO Concepts covered

Interpretation: Role of „time spend‟ to teach a topic?
Typical for OO-topics, not as typical for Non-OO (Selection..)

Schulte, Bennedsen ICER06                                            14
Subgroups: “OO Yes” vs “OO No”
OO concepts covered          Topics that are seen as statistically significant more difficult
No                           Poly&Inheri, Obj&Class, ptr&refs, recursion, DesignClasses,
parameters and Encapsulation
Yes

OO concepts covered       Topics that are seen as statistically significant more relevant
No                        Sel&Iter
Yes                       StatVsNonStat, AdvDataStr, ObjComm, Poly&Inheri, Generics,
Obj&Class, UMLClassDiag, VarTypes, DesignClasses,
DesignSglClass, CRC-cards, MethodDesign and Encapsulation

OO concepts covered       Topics that are seen as statistically significant to be taught on a
higher level
No                        -
Yes                       AdvDataStr, ObjComm, Poly&Inheri, Obj&Class, UMLClassDiag,
DesignClasses, DesignSglClass, CRC-Cards and Encapsulation

b
Schulte, Bennedsen ICER06                                                                          15
Areas of learning programming

Schulte, Bennedsen ICER06       16
Role of Areas

4.5                                                                            70%

4
60%
3.5
50%
3

2.5                                                                   All      40%                                                                        All
OO Yes                                                                              OOYes
2                                                                    OO No    30%                                                                        OO No

1.5
20%
1
10%
0.5

0                                                                             0%
General     notional   notation   structures   pragmatics                    General     Notional   notation +   structures   pragmatics
orientation   machine                                                        orientation   machine

importance                                                                          taught

Schulte, Bennedsen ICER06                                                                                                                      17
Hierarchy of Object Interaction
5

4.5

4

3.5

All
3                                                             Yes
no

2.5

2

1.5
All Scales:
1-5
Underst. & Use:
1
understandable+   useful+   level NOW+   level w anted
Lower=better
Level: Higher=better

Schulte, Bennedsen ICER06                                                                     18
Teaching OO                                 Teaching PROC

          procedural topics

              OO topics                  

                  Areas                   
           Object Interaction            
Overall: very similar
Schulte, Bennedsen ICER06                                           19
Topics assigned to Areas
(by the authors)

Topics                                             Du Boulay area

Sel&Iter, Parameters, Scope, Syntax,               Notation
UMLClassDiag, Ptr&Refs, Library

Generics, Poly&Inher, Encapsulation

ObjComm, MentalModel, StatNonStat, VarTypes,       Notional machine
Obj&Class

Debugging, IDE, CRC-cards, DesignSglClass,         Pragmatics
DesignOfClasses, MethodDesign, AlgDesign,

Ethics, AlgEfficiency                              General Orientation

Schulte, Bennedsen ICER06                                                20
Areas Topics: relevance

4.5

4

3.5

3

2.5                                                                        All
OO Yes
2                                                                        OO No

1.5

1

0.5

0
General         Notional   Notation++   Structures   Pragmatics
Orientation      machine+

Schulte, Bennedsen ICER06                                                              21
Areas compared
topics                                                                         du Boulay
4.5                                                                            4.5

4                                                                              4

3.5                                                                            3.5

3                                                                              3

2.5                                                                   All      2.5                                                                   All
OO Yes                                                                         OO Yes
2                                                                    OO No     2                                                                    OO No

1.5                                                                            1.5

1                                                                              1

0.5                                                                            0.5

0                                                                              0
General      Notional   Notation++   Structures   Pragmatics                    General     notional    notation   structures   pragmatics
Orientation   machine+                                                         orientation   machine

Schulte, Bennedsen ICER06                                                                                                                           22
Summary / Conclusions

• „Classic‟ topics /iteration syntax) similar relevance, level
•    Including OO in CS1 seems to be an addition of topics
•    OO-topics are seen more difficult by those who do not
teach them
• OO Teachers have a tendency to rate „abstract concepts‟
as less difficult (table)

• Notional machine
• Least relevant (areas)
• More relevant in OO (topics, but…)

• Hidden curriculum (structures vs. notation)
• Focus on coding in OO, too
(notation vs. notional machine)

Schulte, Bennedsen ICER06                                         23
Teaching OO                                  Teaching PROC

              procedural topics

                   OO topics               

                     Areas                 
    Notional machine

               Object Interaction         

Schulte, Bennedsen ICER06                                            24
Thank you!

Schulte, Bennedsen ICER06                25

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