1

Distance Learning on Forty Cents a Day

John SullinsDepartment of Computer Science and Information Systems

Youngstown State University

2

Overview

• Goal: Enable students with time conflicts to take courses

• Asynchronous Learning– Powerpoint slides for lectures– Recorded summaries of lectures– Downloaded and used together by distance learning students

• What was learned:– Ideas for recording lectures– Best practices for exams and presentations– Effects on in-class students– Workload involved

3

The Situation Then

• Course:– CSIS 5857: Encoding and Encryption

• Elective for undergraduate and graduate students• Emphasis on mathematics and algorithms

– Offered Spring 2007, MW 3:00 – 4:15

• Time conflict for several graduate students– Most CSIS graduate students work full time

– Security topics of most interest to these students

• Students asked for distance learning option in January– Too late to reserve distance learning classroom

– No time to acquire distance learning equipment

4

The Situation Now

Fall 2007• CSCI 5895: Artificial Intelligence in Game Design

– Emphasis on concepts and design

– Some programming

• CSCI 6962: Server-side Design– Heavy emphasis on programming

5

Procedure Summary

Slides prepared for

lecture

Recorded lecture

summary

Lecture given to in-class students

Slides posted to web site

Corrections made

Class contributions

to lecture

Recording posted to web site

Slides and recording

downloaded by student

6

Recording Procedure

• Synchronized with slides– Separate recording for each slide

• Introduce slide

• Describe slide

• Tell to go to next slide

– Edited together to create entire lecture• Usually shorter than actual lecture

– 75 min. lecture 20 – 30 min. recording– 50 min. lecture 15 – 20 min. lecture

7

Recording Procedure

“In this slide we will introduce a potential weakness of RSA if it is used to send very short message, particularly if an adversary knows the form of that message…

Please go to slide 5”

“In this slide, we’ll do an example of a short message attack. Let’s say that Darth knows that Bob will send Alice a Social Security Number (which he knows is exactly 9 digits), encrypted with her public key. Let’s also suppose that Darth knows that public key…

Please go to slide 6”

“In this slide, we’ll see how Darth can use Alice’s public key to encrypt all possible social security numbers and store them in a big table. Since there are only a billion or so, this can easily be done…

Please go to slide 7”

… …

8

Listening to Lectures

• Course web site provides slides and audio files of recordings– Student downloads files

– Listens to recording

– Follows along with slides

• Useful idea: Create introductory lecture– Gives students practice in following along with lecture and slides

– Early detection of technical difficulties

– Allows students to give quick feedback about lecture style

9

Recording Lectures

• Recorded soon after in-class lecture– Made recording smoother, as talk already given once

– Allowed correction of slides• Mistakes found during lecture• Mistake-free slides more crucial for on-line students

– Allowed summary of in class discussion to become part of recording• More complete coverage of topic• On-line students become more of a part of class• Important to write these down immediately after class!

“In class, a student made the point that while you may need to present numbering in international formats, you may want to keep currency in dollars rather than pounds or Euros. In that case, you would use get NumberInstance rather than getCurrencyInstance to set the format of the numbers.”

10

Recording Software

• Software:– Microsoft Sound Recorder

– WavePad

– Both allow files to be appended together to create entire lecture form short recordings

• Recording properties– Sample rate important

• Too low recording unintelligible • Too high Files too large for fast download

– Best compromise:11.025 kHz, 16 Bit, Mono

– Record and test yourself!

11

Slide Creation

• Must be detailed enough to allow student to get information from both slides and voice– More difficult to understand speech over internet than in person

– Key question: Could you get gist of lecture from just slides?

• Some ideas:– Ask question, answer question

– Introduce procedure, then show step by step

12

Slide Creation

• Most time consuming part of process!• Shortcuts:

– Screenshots – Slides from textbook site

• Should not do this the first time you teach a course!

13

Exams for Distance Students

• Exams emailed to students as Word document– Should test ability to receive, open, and save

document in advance

– Agree in advance on day/time

– Must be available to answer questions via email

– Provide more time• Will be using word processor instead of writing• Will need to scan drawings• Usually multiply time by 1.5

– Students email document with answers back• Send receipt indicating you received it!

Me

Student

Document containing exam

Emails with questions

Document containing answers

14

Exams for Distance Students

• No way to proctor exams– Trust students not to use notes

– No exams (just projects and papers)

– Open book/notes exams• Some trust still required!

• Exams focus on “problem solving”– Better test of “real world” situation

• Examples:– “Darth Vader has infiltrated your

company” questions

– “Barney Fife is your new chief of security” questions

While auditing Darth’s computer, you notice that he is running a program which is generating all possible different credit card numbers and encrypting them with the organization’s public key.

What would you suspect that Darth is trying to do?

Barney has invented a new cipher called “quadruple DES”, which uses 4 56-bit keys applied sequentially (much the same way triple DES applies 3 56-bit keys sequentially).

Explain to Barney why this is not significantly more secure than triple DES.

15

Suitable Students

• Take class on line because can’t come to class– Full time job during day classes

– Conflict with another class

– Must miss significant part of semester• Student had to travel overseas for 7 weeks

– No students who can come to regular lecture, but “don’t want to”

• Able to make arrangements to come to class once or twice – Must give advance notice and be flexible with days

– Example: Final research presentation in 5857 • On-line students given choice of 4 possible days• All were able to come to at least one

• Very computer literate– Will probably need to do programming assignments at home

– Must be able to install and run software with little or no help

16

Effects on In-Class Students

• Overall positive effect– No effect on class attendance

– Most students printed slides beforehand to take notes on

• Far more effective than attempting to copy complex encryption system diagrams

– Several students used recordings as study guides

• Overall better grades than in previous year

17

Effects on In-Class Students

• Potential negative effect– Students can become less engaged

– Seems to be more true in undergraduate class

• Effect of detailed slides– Students less interested in taking notes

• Solutions:– Keep slides entertaining

• “Oswald the indecisive orc”

– Ask questions• “What games have you personally

seen this behavior in?”

– Worst case: Don’t post slides until after in-class lecture

18

Conclusions

• Asynchronous distance learning can be done at little cost– Web site

– Recording software

– Presentation software

• Requires creativity and hard work

• Very successful results for distance learning students– 4 distance learning students in CSIS 5857 all got A’s

– Distance learning students in CSCI 5895 and 6962 have done well so far

– Very positive feedback from all distance students

• Changes made to accommodate distance learning has benefited all students