ITiCSE 2014, Day 3, Final Session, “CS Ed Research”, #ITiCSE2014 #ITiCSE

The first paper, in the final session, was the “Effect of a 2-week Scratch Intervention in CS1 on Learners with Varying Prior Knowledge”, presented by Shitanshu Mirha, from IIT Bombay. The CS1 course context is a single programming course for all freshmen engineer students, thus it has to work for novice and advanced learners. It’s the usual problem: novices get daunted and advanced learners get bored. (We had this problem in the past.) The proposed solution is to use Scratch, because it’s low-floor (easy to get started), high-ceiling (can build complex projects) and wide-walls (applies to a wide variety of topics and themes). Thus it should work for both novice and advanced learners.

The theoretical underpinning is that novice learners reach cognitive overload while trying to learn techniques for programming and a language at the same time. One way to reduce cognitive load is to use visual programming environments such as Scratch. For advanced learners, Scratch can provide a sufficiently challenging set of learning material. From the perspective of Flow theory, students need to reach equilibrium between challenge level and perceived skill.

The research goal was to investigate the impact of a two-week intervention in a college course that will transition to C++. What would novices learn in terms of concepts and C++ transition? What would advanced students learn? What was the overall impact on students?

The cohort was 450 students, no CS majors, with a variety of advanced and novice learners, with a course objective of teaching programming in C++ across 14 weeks. The Scratch intervention took place over the first four weeks in terms of teaching and assessment. Novice scaffolding was achieved by ramping up over the teaching time. Engagement for advanced learners was achieved by starting the project early (second week). Students were assessed by quizzes, midterms and project production, with very high quality projects being demonstrated as Hall of Fame projects.

Students were also asked to generate questions on what they learned and these could be used for other students to practice with. A survey was given to determine student perception of usefulness of the Scratch approach.

The results for Novices were presented. While the Novices were able to catch up in basic Scratch comprehension (predict output and debug code), this didn’t translate into writing code in Scratch or debugging programs in C++. For question generation, Novices were comparable to advanced learners in terms of number of questions generated on sequences, conditionals and data. For threads, events and operators, Novices generated more questions – although I’m not sure I see the link that demonstrates that they definitely understood the material. Unsurprisingly, given the writing code results, Novices were weaker in loops and similar programming constructs. More than 53% of Novices though the Scratch framing was useful.

In terms of Advanced learner engagement, there were more Advanced projects generated. Unsurprisingly, Advanced projects were far more complicated. (I missed something about Most-Loved projects here. Clarification in the comments please!) I don’t really see how this measures engagement – it may just be measuring the greater experience.

Summarising, Scratch seemed to help Novices but not with actual coding or working with C++, but it was useful for basic concepts. The author claims that the larger complexity of Advanced user projects shows increased engagement but I don’t believe that they’ve presented enough here to show that. The sting in the tail is that the Scratch intervention did not help the Novices catch up to the Advanced users for the type of programming questions that they would see in the exam – hence, you really have to question its utility.

The next paper is “Enhancing Syntax Error Messages Appears Ineffectual” presented by Paul Denny, from The University of Auckland. Apparently we could only have one of Paul or Andrew Luxton-Reilly, so it would be churlish to say anything other than hooray for Paul! (Those in the room will understand this. Sorry we missed you, Andrew! Catch up soon.) Paul described this as the least impressive title in the conference but that’s just what science is sometimes.

Java is the teaching language at Auckland, about to switch to Python, which means no fancy IDEs like Scratch or Greenfoot. Paul started by discussing a Java statement with a syntax error in it, which gave two different (but equally unhelpful) error messages for the same error.

if (a < 0) || (a > 100)
  error=true;

// The error is in the top line because there should be surrounding parentheses around conditions
// One compiler will report that a ';' is required at the ||, which doesn't solve the right problem.
// The other compiler says that another if statement is required at the ||
// Both of these are unhelpful - as well as being wrong. It wasn't what we intended.

The conclusion (given early) is simple: enhancing the error messages with a controlled empirical study found no significant effect. This work came from thinking about an early programming exercise that was quite straightforward but seemed to came students a lot of grief. For those who don’t know, programs won’t run until we fix the structural problems in how we put the program elements together: syntax errors have to be fixed before the program will run. Until the program runs, we get no useful feedback, just (often cryptic) error messages from the compiler. Students will give up if they don’t make progress in a reasonable interval and a lack of feedback is very disheartening.

The hypothesis was that providing more useful error messages for syntax errors would “help” users, help being hard to quantify. These messages should be:

  • useful: simple language, informal language and targeting errors that are common in practice. Also providing example code to guide students.
  • helpful: reduce the number of non-compiling submissions in total, reduce number of consecutive non-compiling submissions AND reduce the number of attempts to resolve a specific error.

In related work, Kummerfeld and Kay (ACE 2003), “The neglected battle fields of Syntax Errors”, provided a web-based reference guide to search for the error text and then get some examples. (These days, we’d probably call this Stack Overflow. 🙂 ) Flowers, Carver and Jackson, 2004, developed Gauntlet to provide more informal error messages with user-friendly feedback and humour. The paper was published in Frontiers in Education, 2004, “Empowering Students and Building Confidence in Novice Programmers Through Gauntlet.” The next aspect of related work was from Tom Schorsch, SIGCSE 1995, with CAP, making specific corrections in an environment. Warren Toomey modified BlueJ to change the error subsystem but there’s no apparent published work on this. The final two were Dy and Rodrigo, Koli Calling 2010, with a detector for non-literal Java errors and Debugging Tutor: Preliminary evaluation, by Carter and Blank, KCSC, January 2014.

The work done by the authors was in CodeWrite (written up in SIGCSE 2011 and ITiCSE 2011, both under Denny et al). All students submit non-compiling code frequently. Maybe better feedback will help and influence existing systems such as Nifty reflections (cloud bat) and CloudCoder. In the study, student had 10 problems they could choose from, with a method, description and return result. The students were split in an A/B test, where half saw raw feedback and half saw the enhanced message. The team built an error recogniser that analysed over 12,000 submissions with syntax errors from a 2012 course and the raw compiler message identified errors 78% of the time. (“All Syntax Errors are Not Equal”, ITiCSE 2012). In other cases, static analysis was used to work out what the error was. Eventually, 92% of the errors were classifiable from the 2012 dataset. Anything not in that group was shown as raw error message to the student.

In the randomised controlled experiment, 83 students had to complete the 10 exercises (worth 1% each), using the measures of:

  • number of consecutive non-compiing submissions for each exercise
  • Total number of non-compiling submissions
  • … and others.

Do students even read the error messages? This would explain the lack of impact. However, examining student code change there appears to be a response to the error messages received, although this can be a slow and piecemeal approach. There was a difference between the groups, but it wasn’t significant, because there was a 17% reduction in non-compiling submissions.

I find this very interesting because the lack of significance is slightly unexpected, given that increased expressiveness and ease of reading should make it easier for people to find errors, especially with the provision of examples. I’m not sure that this is the last word on this (and I’m certainly not saying the authors are wrong because this work is very rigorous) but I wonder what we could be measuring to nail this one down into the coffin.

The final talk was “A Qualitative Think-Aloud Study of Novice Programmers’ Code Writing Strategies”, which was presented by Tony Clear, on behalf of the authors. The aim of the work was to move beyond the notion of levels of development and attempt to explore the process of learning, building on the notion of schemas and plans. Assimilation (using existing schemas to understand new information) and accommodation  (new information won’t fit so we change our schema) are common themes in psychology of learning.

We’re really not sure how novice programmers construct new knowledge and we don’t fully understand the cognitive process. We do know that learning to program is often perceived as hard. (Shh, don’t tell anyone.) At early stages, movie programmers have very few schemas to draw on, their knowledge is fragile and the cognitive load is very high.

Woohoo, Vygotsky reference to the Zone of Proximal Development – there are things students know, things that can learn with help, and then the stuff beyond that. Perkins talked about attitudinal factors – movers, tinkerers and stoppers. Stoppers stop and give up in the face of difficulty, tinkers fiddle until it works and movers actually make good progress and know what’s going on. The final aspect of methodology was inductive theory construction, while I’ll let you look up.

Think-aloud protocol requires the student to clearly vocalise what they were thinking about as they completed computation tasks on a computer, using retrospective interviews to address those points in the videos where silence, incomprehensibility or confused articulation made interpreting the result impossible. The scaffolding involve tutoring, task performance and follow-up. The programming tasks were in a virtual world-based pogromming environment to solve tasks of increasing difficulty.

How did they progress? Jacquie uses the term redirection to mean that the student has been directed to re-examine their work, but is not given any additional information. They’re just asked to reconsider what they’ve done. Some students may need a spur and then they’re fine. We saw some examples of students showing their different progression through the course.

Jacquie has added a new category, PLANNERS, which indicates that we can go beyond the Movers to explain the kind of behaviour we see in advanced students in the top quartile. Movers who stretch themselves can become planners if they can make it into the Zone of Proximal Development and, with assistance, develop their knowledge beyond what they’d be capable of by themselves. The More Competent Other plays a significant role in helping people to move up to the next level.

Full marks to Tony. Presenting someone else’s work is very challenging and you’d have to be a seasoned traveller to even reasonably consider it! (It was very nice to see the lead author recognising that in the final slide!)

 



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