Question: Best PLab demo ideas for a large group?

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by pdhixenbaugh | November 13, 2017 15:59 | #15177

Hey all!

What Public Lab activities would you recommend for a 30 min activity with a large group? With the goal of introducing folks to citizen science and giving them a memory of public lab that will stay with them. :)

As I mentioned to some of you at this most recent Barnraising, I work at an outdoor education place. In a few weeks, I'll have the chance to spend 30 minutes teaching the whole staff (of about 60 people) anything of my choice.

My go-to idea was the foldable spectrometer that folks could make themselves in groups of two, and use to investigate the spectra of everyday objects.

And then possibly have a demonstration station set up later with one of the more precise spectrometers and show how it can be used to look at the water from our pond and compare it to the spectral workshop database.

What can people add to this, or suggest as an alternative? I'm also going to apply for organizer event funding for the materials.

Thanks all!


I've done spectrometer building with people -- that works pretty well, although it's good to practice first. Balloon mapping is a bit much for 30 minutes.

You could also bring some UV lights and look at whether things fluoresce or not? Pond water might fluoresce due to vegetation or microbes, or due to oil. Could be interesting to compare -- you could use this nail polish hardening UV light which is UV powered:

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Hi Patrick! I just did this one with a group of about 80. It's an hour, but I'm sure it could be shortened. It's more conceptual "how we build ideas and knowledge" but still a bit hands on.

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Can you go outside? I'd say the classic kite + camera flight, followed by mapmaking is still a crowd-pleaser! To make it super short, you could already have a balloon inflated with a camera going that you could bring our group outside to do a selfie under, then haul the balloon down and look at the picture and georeference it in mapknitter

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Is there a plab page with instructions for what to get, and how to do it?

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Hi Patrick,

With 60 people, 30 minutes is barely enough time to go outside and come back in, even without doing anything at either place. So you might be limited to doing a demonstration instead of participatory project.

It might not be worthwhile buying $80 worth of helium just so people can see what a balloon looks like inflated, although a five foot inflated balloon is a very good way to make people remember something. Ballooning and kiting are so weather dependent that either activity could be less than successful during any assigned 30 minutes. Both require an open, safe area, and kiting requires a big, open, safe area and some practice. In 30 minutes you might have to choose between watching a kite or balloon and looking at the aerial photos taken from one. Unless you have a few well trained assistants, it's hard to do both.

So I like your original idea of using the smart phone spectrometer. I takes longer than 30 minutes for a first-timer to make one, but you could make 10 or 20 of them in advance in about a day. If you do a good job building them, it will take people about 10 minutes to make adjustments for their phones and figure out how to take good photos (exposure, zooming, aiming, etc). Or a similar time to figure out how to connect to Spectral Workbench to see a spectrogram of the photos or video they take.

If you have some accessible fluorescent lamps that people can walk right up to and point their phones at, you can get the compelling spectrum of distinct emission lines. If they can connect to Spectral Workbench, people can use that image to calibrate the spectrometer. By the time they figure out how to do that there will not be any time left to take a spectrum of something else and use spectroscopy to learn something new. But they can take their spectrometers home and do that.

The plans to make them are here: You can hand these out so people who don't take home an assembled one get something. It looks like the store is out of the $10 kits. Jeff might have plans for a new version.

If you want to do a demonstration, you can use a calibrated spectrometer to capture the spectrum of something biological like chlorophyll. Sunlight or incandescent light passing through a suspension of blended fresh leaves (spinach or algae) in alcohol or even water will have a lot of the blue and/or red end of the spectrum absorbed (notes). This is usually easy to see and easy to explain with science.


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