The
goal of most labs is for students to be able to connect the classroom
principles with the real world, and take knowledge from concrete to
discrete. In some cases, students are not yet comfortable with what the
lab is trying to show, and can be following blindly a recipe
without realizing where they are going (or that they have left
off a critical, perhaps implicit step.)
Preparation for lab:
- Go through the lab yourself at a lab station.
- Note where steps are not clear, or where the lab assumes knowledge that students may still be lacking.
- Note places where assistance is likely required, such as parts, checkoffs, or demonstrations.
Outline for lab:
- Announcements
- A very brief outline of the high-level purpose of the lab.
(Example goal: examine frequency response of RC low pass and high pass
network. Why: filters critical for separating different frequency
components, smoothing signals, removing noise. Example: bass/treble
adjust in audio system.) It is surprising that students get so bogged
down in the details of doing the lab exercise that they can easily lose
sight of the purpose of the lab.
- One or two pointers/mini demos on anticipated common
pitfalls. A classic example is having the compensation network on the
oscilloscope probe misadjusted, so that a square wave has peaks or
looks low pass filtered. You could use a projector or for a small
section, have everyone see directly on the oscilloscope.
- Perhaps have everyone do something quick at their station
to match the demo- tell them to start the lab once it works, or to ask
for assistance if it is not working.
- This initial talk takes time away from doing the lab, so
the demo should only be something that will really help students
do the lab more effectively.
- Answer questions.
- If getting lots of questions, queue questions on board.
- If getting many of the same questions (say 3 or 4 similar
question in a row), it is probably worthwhile to make an
announcement/correction to whole class. Write this announcement on the
board. Then when question is asked again, students can read response on
board.
- If no questions, wander around- is someone stuck and not realizing it, or too shy to ask a questions?
- ``Its not working. Can you make it work for me?'' What's
not working? What do you expect to see? Did you check that all
equipment and probes are working correctly? Are your input waveforms
correct? Are your power supplies and grounds connected properly? Are
waveforms correct at intermediate points? Do you see the same signal at
both ends of a wire connection?
- ``Its not working. I need a new resistor/capacitor/transistor/station/oscilloscope.'' How do you know the component is defective? Show me that it is bad.
- ``Why doesn't the waveform on the oscilloscope look like in the book/lab manual?'' One
thing to watch out for is aliasing with a digital oscilloscope. With a
digital oscilloscope, you almost need to know what the waveform is to
set up the correct sweep rate.
- In general, if a question is something within the scope of
the course/lab that students could answer themselves, encourage them to
do so by guiding questions. If it is outside the scope of the class,
for example aliasing issues in EE40, a quick answer of ``sample rate
should be 100X highest frequency of interest, so you need to set the
sweep rate to X'' is good.
If time allows, a query to see if the student really understands what
they are showingis useful. For example, on an oscilloscope check,
scrambling all the controls and student being able to get waveform
correctly again would demonstrate competence.
Last 15 minutes
- Let students know lab is almost over.
- I would suggest giving priority in last 15 minutes to
students who have checkoffs to get signed off. Students will be
frustrated if they completed the work but have to come back because
they are missing a signoff.
- While it is nice to be able to stay a bit after lab period,
students may plan better or work more efficiently if they know they
will only have the 3 hour lab period.
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