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It Seemed Like a Good Idea at the Time…

It Seemed Like a Good Idea at the Time…. Katherine Deibel University of Washington. drizzly. It was a dark and stormy night at the University of Washington… 90 minutes until latest Data Structures project was to be turned in… I was the graduate TA…. My apartment, 10:30pm…

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It Seemed Like a Good Idea at the Time…

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  1. It Seemed Like a Good Idea at the Time… Katherine Deibel University of Washington

  2. drizzly It was a dark and stormy night at the University of Washington… 90 minutes until latest Data Structures project was to be turned in… I was the graduate TA…

  3. My apartment, 10:30pm… Nursing the aches of a first year graduate student course load… Undergraduate TA handling the turnin at midnight… I decided to check e-mail one last time before bed…

  4. CHAOS! PANIC! Students could not log in… programs were freezing… I contacted a student by IM… I realized I had to handle this personally…

  5. Undergraduate lab, 11:00pm… All students were panicking … I managed to find a terminal with ‘top’ running… I yelled for my students to terminate their programs… It was too late…

  6. I got to bed about 1:30AM

  7. So What? • An assignment crashed a server… big frickin’ deal right? • But this assignment had been used before with no problems… What was different this time?

  8. The Programming Assignment • Word Frequency Analysis Tool:Implement an unbalanced BST, AVL tree, and a Splay tree where a node <key, value> represents <word, frequency> • Extra Credit:Use gprof to profile your three trees. Run your trees on two inputs: • Any file from Project Gutenberg • The provided file: words.txt a.k.a. The Unix Dictionary

  9. Let’s Do The Math… Unbalanced BST + 45,424 ordered words = BAD (1) (1) + code profiler running = MORE BAD (2) (2)  >6 instances running on the same server = REALLY BAD (3) (3)  all instances running at same priority = SERIOUSLY REALLY AWFULLY BAD

  10. Again… So What? • The lesson is • Use a smaller file next time or • Teach the students to use ‘nice’ • True, but… • This had not been a problem before • Some students successfully profiled their code • Again, what was different? • Something motivated more students to do the extra credit than in previous course offerings

  11. A New [Better] Grading Policy • Joint decision and effort by myself and the undergraduate TA • Both of us graded the assignments • I graded the theory side: • Correctness, • Complexity • Generalizability • Hannah graded the software engineering side: • Programming style • Documentation

  12. Before: Summative assessment Surface grading of code Few grader comments Correctness most important element Style worth 1-2 pts Programs worth 20 pts Perfect scores common Now: Formative assessment Deep grading of code Many grader comments All elements weighed equally Style worth 20+ pts Programs worth 80+ pts More points lost What This Change Meant Students panicked about grades!

  13. The Mystery Solved • We failed to emphasize • Non-perfect scores were expected • Performance would be curved • Students leapt at chance to recover points • More students doing extra credit • More strain on undergraduate servers

  14. Our Mistakes: Redux • Provide too large of an input file • Should have taught students about ‘nice’ • Changed grading policies without addressing underlying student culture about grades and points • Checking my e-mail that one last time before bed

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