CS Education Chat with Mike Dunlavey

I had a nice chat with Mike Dunlavey about CS education, teaching newcomers to code and the challenges CS teachers commonly face and some ways we deal with those challenges.

Transcript

The following transcript was automatically generated by an algorithm.

00:00 : you have us some teaching experience
00:03 : right at bc is that boston college
00:06 : yes okay um
00:09 : and you have a lot of insights about
00:11 : teaching as well
00:13 : and i like to dig a little bit into that
00:15 : um
00:16 : i was i'm also curious like whether
00:19 : you've taught your students this
00:22 : technique
00:22 : and how they have taken how they took it
00:27 : i honestly don't remember um because the
00:31 : courses i taught
00:32 : the first the first course was was basic
00:36 : yet i mean because this was in the
00:38 : school of management and they had
00:40 : they taught computer science in the
00:41 : school of management and back then we
00:43 : were teaching basic
00:45 : and uh you know performance is the last
00:48 : thing on your mind
00:49 : you want to just get it to do yeah
00:52 : that's true you need to make
00:53 : something interesting yeah you need to
00:55 : be at a pretty high level before this
00:57 : comes into play
00:58 : yeah and you know i would get them
01:01 : get them teach them enough techniques
01:04 : so that they could uh start a project of
01:08 : their own design you know like
01:09 : one would say we want to simulate
01:12 : sailing a sailboat
01:14 : another one would say we want to have
01:15 : bank accounts for the family
01:17 : mother want to say we want to we want to
01:19 : play music and show the flag going on
01:22 : there
01:23 : these were apple computers and
01:26 : uh so if they could get that that was
01:29 : great
01:30 : um then the the the second course was
01:33 : pascal so you could start talking about
01:35 : data structures
01:37 : i mean you could talk about data
01:38 : structures sort of in basic
01:41 : but you know but pascal really had
01:45 : structures and uh upper and lower case
01:50 : oh wait a second did it no no c had
01:53 : upper and lower case
01:54 : but c was a new thing at that time
01:58 : um but then i moved from from there to
02:01 : list talking about ai well again you're
02:03 : not concerned about performance you're
02:05 : concerned about
02:06 : you know how do you how do you write a
02:08 : program that does something
02:10 : semi-intelligent and uh
02:14 : it never really came up and then let's
02:17 : see a course on operating systems were
02:19 : there you're all about you know how do
02:20 : you do
02:21 : files stuff like that
02:25 : yeah it didn't really come up i see
02:28 : but that doesn't make sense it did yeah
02:32 : it makes sense yeah if you're
02:33 : teaching you're just trying to teach
02:35 : people
02:37 : how to get into programming um
02:40 : this is this is gonna come far down the
02:43 : road
02:44 : um uh what are your
02:47 : biggest sort of um
02:50 : insights or realizations about teaching
02:55 : well the first the very first thing i
02:58 : learned
02:59 : was that you gotta go slow in fact
03:03 : because things things that are that seem
03:05 : obvious to you are not obvious to the
03:07 : students
03:09 : like you know in teaching basic
03:12 : what i've what i found in teaching basic
03:15 : was that the first thing i did was write
03:17 : a little interpreter for a decimal
03:19 : computer
03:20 : so i could start give about six weeks
03:24 : having the students do do
03:28 : examples on this decimal computer where
03:31 : just
03:31 : simple things like add up a bunch of
03:34 : numbers
03:35 : or uh or you know write a write a loop
03:39 : or add two numbers and and
03:42 : show the result and this computer had
03:46 : had decimal instructions decimal numbers
03:50 : in the in the memory it had a memory of
03:53 : like 100
03:54 : memory locations and so so the whole
03:57 : concept of a memory location
04:00 : as and and computers doing one step at a
04:04 : time because
04:05 : when they ran the the interpreter they
04:08 : there was no
04:08 : there was no run button you had to
04:11 : single step it
04:13 : oh really written in basic point is i
04:16 : want to get across this is what
04:18 : computers do
04:19 : they do one thing at a time and they're
04:22 : really
04:23 : stupid they don't read your mind i mean
04:26 : because these
04:26 : kids would hit him with basic you know
04:30 : there's a statement that says if if blah
04:32 : blah blah
04:34 : okay they say well that means it knows
04:36 : english
04:37 : and all i can do and all i have to do is
04:39 : tell it in english what i want
04:42 : so i think that i think that you uh as
04:45 : as sort of like a construct of your
04:48 : teaching you
04:48 : set it up so that they couldn't just
04:52 : run the program that they were forced to
04:54 : single step it or
04:56 : was that like initially initially
04:58 : initially
04:59 : so that they understood got it that's
05:01 : really
05:02 : that's a really clever idea i like it
05:05 : because
05:05 : because you you know you use a variable
05:08 : you say
05:09 : x equals three plus y you know they say
05:12 : oh okay it must know english you don't
05:16 : you have to get them to understand that
05:19 : x is a memory location and y
05:21 : is a memory and a memory location is
05:23 : something that can hold
05:24 : one number you know
05:28 : if you if you say x equals
05:31 : three and then you say x equals five
05:33 : well it's no longer
05:34 : three you know just
05:38 : really this is stuff that as a
05:41 : programmer if you've been programming
05:42 : since you were a kid
05:43 : like like they are now you you don't
05:47 : even think that
05:48 : yeah yeah actually yeah from um
05:51 : from talking to my former professor
05:54 : mark gustile uh he he told me that one
05:58 : one of the biggest things that
06:00 : beginners get tripped up is the fact
06:02 : that you can say
06:04 : x equals x plus one and
06:07 : that's like a mind bender for beginner
06:12 : how can x be equal to x plus one i don't
06:15 : get it
06:18 : yep that's that's the uh
06:22 : that's one another one is uh swapping a
06:24 : and b
06:26 : if you say a equals b and b equals a
06:29 : well then
06:29 : what you have to have a temp you have to
06:32 : have a time yeah yeah
06:35 : you're getting really good you use this
06:37 : by moving things from hand to hand
06:39 : you know when you drop something maybe
06:42 : yep
06:44 : yep that's true that's true but
06:48 : you know if you've been you've been
06:50 : doing coding
06:52 : uh teaching you said
06:55 : uh uh yeah yeah yeah i did some teaching
06:58 : for a uh for coding boot camp in
07:02 : atlanta which is something that
07:05 : you know they take adults that want to
07:08 : change their career
07:09 : and and move into software development
07:13 : and they put it into my class
07:16 : or one of my uh you know one of the
07:19 : other
07:20 : instructors class for 16 straight weeks
07:24 : and then it's a boot camp we we
07:29 : we try to get them ready for to be hired
07:33 : uh in that amount of time and it's
07:36 : kind of crazy uh it works some
07:39 : percentage of the time
07:41 : um for for so for some percentage of the
07:44 : people
07:45 : and i'm really proud of that work uh but
07:48 : yeah i
07:48 : i served that dove head first into
07:51 : teaching
07:53 : and yeah yeah like before that i didn't
07:56 : really have
07:57 : real teaching experience so it was just
08:00 : like a root
08:01 : awakening um you know
08:04 : in a lot of respects like in terms of
08:06 : what
08:07 : works what doesn't work and yeah i
08:09 : definitely have the same realization of
08:10 : like
08:12 : no no matter who you are i think like
08:16 : well especially if you're like skilled
08:19 : at some field and you never taught
08:21 : before and you start to teach
08:24 : you're just gonna go too fast for them
08:26 : initially
08:28 : and then and then hopefully you will
08:30 : make adjustments
08:31 : after that
08:35 : yeah uh yeah yeah uh you know i go ahead
08:40 : i mean
08:41 : you know i was teaching kids who were
08:44 : freshmen and
08:45 : sophomores in sometimes juniors
08:48 : in college and they had had no pro
08:51 : occasionally somebody had a programming
08:53 : class
08:54 : in high school uh so they were all
08:57 : pretty much at a level i could predict
09:01 : yeah yeah well in regards to single
09:04 : stepping i i
09:06 : use a tool called python tutor
09:10 : um so
09:13 : so what you do is with python tutor
09:17 : is can you still see my screen yes yes
09:20 : okay so let's say you write a very
09:22 : simple program
09:25 : that is gonna sum up in i'm gonna
09:28 : loop from 0 to 10 and then sum
09:32 : sum up the numbers
09:36 : uh what you do is you say visualize the
09:39 : execution of this program
09:42 : and then this is like a vcr you can
09:45 : step forward or you can step backwards
09:48 : and the key is you can step
09:49 : backwards okay and i try to
09:52 : force my students to do this um
09:56 : when they have this one of the things
09:58 : that's important in there
10:00 : is the indentation they then
10:05 : they will not assume that um
10:08 : and that the the indentation is
10:11 : important
10:13 : oh yeah yeah yeah the students it takes
10:16 : them a while to forget to figure out the
10:19 : indentation part yeah
10:21 : that's interesting yeah
10:25 : and and i guess for some of them i don't
10:28 : know i i
10:28 : i swear initially i like for the first
10:31 : class that i taught
10:32 : i taught them javascript first
10:36 : and then the second one that i taught i
10:38 : decided to
10:39 : try python first and i've i found that
10:43 : it went much better with python first
10:47 : i think it's a combination of there's
10:51 : just less syntax
10:52 : they have to type with python so
10:55 : just having to type less means there's
10:58 : less chance for
10:59 : mistakes especially for especially
11:02 : with with uh javascript or c
11:06 : you have to match up the curly brackets
11:10 : that are on that are kind of far apart
11:12 : right one is on
11:14 : one is here the other line is like five
11:17 : lines down you have to match up those
11:18 : brackets
11:19 : and they will often forget with python
11:22 : that's not an
11:22 : issue because there are no brackets like
11:25 : that
11:26 : um and and i think
11:29 : i think python has much better error
11:31 : messages when they happen
11:33 : and and there's this tool so it did
11:36 : go better with python than javascript
11:39 : javascript is like a famously
11:40 : unforgiving language
11:43 : well then that's that's important the
11:46 : single stepping is important
11:48 : and another thing that's important is to
11:50 : be able to
11:51 : once you know one language then to be
11:54 : able to learn a new one
11:57 : yeah yeah that's true i
12:00 : i think that shaw is is a guy he
12:03 : wrote a bunch of tutorials online and
12:07 : he said that by the time you learn
12:11 : the third your third programming
12:13 : language
12:14 : that then you have arrived
12:20 : yeah so so perhaps you and um and you
12:23 : probably want to like
12:24 : do languages that are kind of different
12:28 : to to get a sampling of the different
12:30 : styles
12:31 : maybe i don't know well there are things
12:34 : you know when you know like in this case
12:37 : okay well what
12:38 : range i don't know i wrote it but
12:41 : when you i mean i found in teaching
12:44 : basic that
12:45 : that i could get them going quite well
12:48 : on um scalar variables
12:52 : single single variables when they went
12:54 : to a raise that was a big speed bump
12:57 : um yeah so
13:00 : that was the trick there was a series of
13:03 : speed bumps
13:04 : and a arrays were one of the big ones
13:07 : yeah i raised loops
13:10 : loops were come earlier yeah yeah
13:14 : yeah loops having to do with arrays um
13:17 : with i i probably like i
13:21 : i decided that it was more
13:24 : worthwhile to teach them while loops
13:28 : than than the compacted for loop
13:32 : syntax because each each of the three
13:35 : parts
13:36 : that go into the for loop are set on
13:39 : separate lines
13:40 : if you do it as a while loop and they
13:42 : can be seen
13:43 : as a single step like this the
13:45 : initialization goes before the while
13:47 : loop
13:48 : and then you would do the plus plus
13:50 : counter at the end
13:51 : and then the conditional is in the while
13:54 : loop
13:55 : so i prefer to do it that way
13:58 : and then yeah the arrays and strings
14:02 : those are tricky yeah there were various
14:06 : patterns
14:07 : that i like i gave them like sort of
14:09 : like a template
14:11 : of like well these are it's very common
14:14 : that
14:15 : if you want to need to do like a string
14:19 : some to do something to a string or to
14:21 : do something to an array
14:23 : it's very common that you you do
14:26 : something like this so just follow this
14:28 : template
14:29 : and then fill in the blank i give them a
14:33 : template and they could kind of fill in
14:34 : the blank
14:37 : yeah so it sounds like you've you've
14:39 : been going through some of the same
14:40 : challenges that any
14:42 : new teacher does yeah
14:45 : you know i've i've seen i've seen
14:49 : cases where they start off with message
14:52 : passing
14:53 : and object-oriented programming and then
14:55 : say
14:56 : nobody's gonna know what you're talking
14:58 : about yeah
15:00 : they're like let's talk about
15:01 : encapsulation and
15:03 : polymorphism yeah
15:06 : oh whoa whoa whoa
15:11 : yeah yeah i think i don't know
15:14 : like the java java became such a hot
15:17 : topic
15:19 : like in the 90s for for various colleges
15:23 : um i imagine the teachers that were
15:26 : trying to teach
15:28 : they probably ran into some
15:31 : some challenges back then well
15:34 : i i still get a lot of practice
15:37 : doing the performance tuning mainly
15:40 : because people
15:41 : have been taught um object-oriented
15:45 : programming levels of abstraction
15:47 : they think the more abstraction the
15:49 : better and i'm saying
15:50 : wait a minute you find out that that's
15:53 : what's taking all your time
15:56 : yeah you mentioned that in your paper
15:58 : you said like often you find that
16:01 : the abstraction is the thing
16:04 : is the thing that's causing the
16:06 : performance issue
16:08 : yeah even though if you people are
16:11 : taught to do that
16:13 : on the with the rationale that this will
16:16 : perform better