Die WANDTAFEL - neu entdeckt
http://www.math.harvard.edu/~knill/pedagogy/blackboards/index.html
Blackboard of February 27, 2017, a linear algebra review class.
About Blackboards
Oliver Knill
Just saw
this piece on Slate by Lewis Buzbee.
I agree. Blackboards are terrific. It is probably the overwhelming opinion that in mathematics,
blackboards are the best tool to develop a thought to a class.
They always work and they slow down the speaker enough to get the ideas across clearly.
Powerpoint needs lots of restraint in order to be used effectively. It is rarely done
right. If people use white boards, then just to write down some key words or a quick
drawing. Whiteboards do not work well for complex topics.
A white board in the movie "Arrival".
- Blackboards always work
- It slows the speaker down
- They are readable also from far
- One can attach magnets
Why are white boards implemented then? First of all, it is cheap and this is always an
argument. An other problem is that in many institutions, the people who make
decisions about whether to implement blackboards have no idea. They are folks
who have seen whiteboards in their seminars and so believe that this is cool.
I have taught as a course assistant at ETH Zürich (computer science part), at
University of Arizona all classrooms, I taught in were white boards and it had never
had a good experience.
I had once to give a talk in Vienna, where all the pens were dried out and I had to
give a mathematical talk without board. Since then (for example at the extension school),
I bring my own pens as backup. Next year, I will bring even my own erasing liquid since
the remaining stains are so distracting.
Whiteboards are terrible even for private use. I have had both. During college and also during
my postdoc time at Austin, I had a white board on my wall to work on.
Since 10 years, have a blackboard at home and love it. Here are some pictures:
(from an actual class 2014)
(personal blackboard at home 2014)
(from an actual class 2010)
(Coupled pendulum at blackboard
(personal blackboard at home 2009)
A lecture on May 26, 2017. Click for a larger picture.
May 2015 addition: The overhead projector has been popular a few decades ago.
I had many classes from primary to high school on this device (probably the majority).
One sees the struggle even when great teachers do
an example of a lecture by John Milnor in 1965.
The pen often does not work well. There is only a small part of the lecture visible.
Milnor does the best possible choice with the device. He writes clearly but sometimes, the pen
fails to deliver the ink onto the screen. In that MMA lecture (as in many conferences I have seen
where overheads were used), there were two projectors used in parallel, a luxury which hardly was
available in classrooms.
Slides are used more and more in talks. They are not always used effectively.
Most of the time, the talks become too fast with slides. Similarly in lectures.
The reason is that the teacher does no more have to think. An other reason is
lack of authenticity. Myself in the audience I ask myself, why am I here. I could
look at the slides also at home.
- Slides make the speaker go too fast.
- Slides make the speaker lazy. The speaker does no more need to think
- Most presenters have terrible slides skills.
- Slides need additional technology (computer, projector) which can fail
White boards often do not work (dry markers), or have old marker traces
which are difficult to erase. I had several disasters in this respect.
In one conference, there were no working markers any more available and
had no communication tool except talking. One also tends to write too small with
dry markers and the audience can not read it. In my experience, most presenters
do have a horrible handwriting on white boards. Bad writing can be a problem on blackboards
too but the chalk does not allow too fast and sloppy writing so that most blackboards
are clearer than whiteboards. At last white boards are usually smaller and work only
for smaller groups of students therefore.
- Markers dry out
- Erasing is often problematic
- One has to deal with chemicals in the classroom
- Whiteboards are usually too small
- The presenter writes too fast on whiteboards
- The presenter writes too sloppily on whiteboards
| 
White board in the movie Arrival. This is a pretty neat whiteboard in comparison
what one sees in offices or classrooms.
You see an other whiteboard in room 309 in the Harvard science center. Just open
this picture
and zoom in a bit to the left. A terrible board even so it has been cleaned professionally.
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So, why are white boards or crappy blackboards used? The reason is very simple: administrators
who buy equipment often do not teach themselves or do no more teach. Most of the time it is
also just simply a financial decision as whiteboards appear cheaper at first.
Here is a blackboard talk on my own larger
board at my home office. And an outline on a small 48 x 36 inch chalkboard (a 50+ dollar board).
This small board is not bad. It is not of the quality of my large board but much cheaper. One
consequence is that one has to wash it off very well in order to erase the previous writing. It
would never do in a classroom setting but for having something behind your desk, it is perfect.
Here is a snapshot of my blackboard in the Technion in 1988. The buildings were
some "wood houses" where now a larger computer science complex is located.
I had doodled around with some surfaces:
A short clip from a
This youtube clip
of Jake Wright shows a blackboard scene at ETH, showing the
Picard's existence theorem for ordinary differential equations.
M4V, Ogg Webm.
Document history:
Ein Beispiel von Oliver Knill (Harvard Universität)
https://www.youtube.com/watch?v=9fYEfYMJru8
