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What I taught in the development lab today

After our disastrous chick lab — it turns out that getting fertilized chicken eggs shipped to remote Morris, Minnesota during a blizzard is a formula for generating dead embryos — the final developmental biology lab for the semester is an easy one. I lectured the students on structuralism and how there are more to cells then genes (there’s also cytoplasm and membranes and environment) earlier today. This afternnon I’ve given them recipes for soap bubble solution and told them to play. They’re supposedly making little model multicellular organisms by chaining soap bubbles together, and observing how the membranes follow rules of organization just like the ones we see in living tissue.

In case you’re wondering what the recipe is so you can do it too, here’s my bubble soap formula:

  • 5ml Dawn dishwashing soap

  • 100ml DI water

  • 1ml glycerine

It gets better as it ages — there are perfumes and a small amount of alcohol solvent in the dishwashing liquid which evaporate off with time. The students are playing with concentrations, and if you’re making it up fresh and don’t want to wait until tomorrow, you can increase the concentrations of soap and glycerine.

The more glycerine you add, the more long-lasting the bubbles are…and unfortunately, the heavier they are. If you want bubbles that will waft gently on the breeze, you’ll want less glycerine. It’s a very forgiving recipe, just play.

I’ve also provided the students with a couple of books: the classic Soap Bubbles: Their Colors and Forces Which Mold Them by C.V. Boys, and The Science of Soap Films and Soap Bubbles by Cyril Isenberg. They’re more about math and physics, but they have some nice illustrations. These are projects you can do at home with cheap ingredients bought at the grocery store, so those of you with kids might try playing with it this summer. There are simple rules about the angles of intersection between bubbles — if you’re mathematically inclined, take pictures and use a protractor and see if you can work them out. There’s also some really cool stuff going on with colors, since the bubbles have a gradient of thickness from top to bottom and you get wonderful colors caused by refraction and reflection and phase shifts across the membrane.

OK, if you don’t have kids, you have my permission to play with soap bubbles, too. Tell everyone who looks at you funny that you’re doing Science!

Comments

  1. says

    Putting industrial surfactants in public fountains, though, that’s naughty and literally sophmoric.

    Speaking of bubbles, if you make bubbles with CO2 in them they’re great for putting out fires. Here’s some great pictures of fire extinguishers at Elgin Air Force Base after a test in which they couldn’t be turned off:
    http://izismile.com/2012/05/15/when_fire_extinguishing_system_goes_off_at_an_6_pics.html
    I can’t help but wish there was someone with a video camera to catch the wall of foam when they opened the hangar door.

  2. ChasCPeterson says

    That sounds like a lot of fun.

    take pictures and use a protractor

    Why use a protractor (or a ruler, or a planimeter) when there’s ImageJ? Free to download, measures linear distances, areas, and angles, etc. from any digital photograph. Many educational and scientific applications. I can snap a photo in the field and take measurements later at the bar. Awesome.

  3. says

    I wish I could use ImageJ! It doesn’t support our Pixelink camera (if anyone has a driver for it, let me know), and although I could tell them they have to use µScope for acquisition and ImageJ for analysis, forcing non-computersci geeks to learn two programs to do the labs is a bit much.

    So really, if anyone knows of a Pixelink+ImageJ combo that works, tell me. If it’s a combination that works on a Mac so I can ditch the ugly little PC in my lab that does nothing but image capture, I might be willing to bear your children for you.

  4. llewelly says

    “They’re supposedly making little model multicellular organisms by chaining soap bubbles together, and observing how the membranes follow rules of organization just like the ones we see in living tissue.”

    In fact you are conducting experiments which will reveal the insidious truth about the effects of bubble bath on young, vulnerable minds.

  5. Mattir, Another One With Boltcutters says

    Saved for the hapless Cub Scouts that DaughterSpawn and I torment on Tuesday evenings…

    Bwahahaha!

  6. nonotthatla says

    Reminds me of our 3-winter sojourn in Cloquet, MN, several years ago. We discovered that soap bubbles last for days when you make them at -25F. When they hit the snow, some of them crack open like eggs.

  7. prfesser says

    Corn syrup also works and is cheaper than glycerin, for the students who want to continue science-ing at home. And a wide strip cut from the bottom of an old T-shirt, or a loop of cloth mesh, holds more bubble solution and can make rather large bubbles. We did this about 30 years ago at Virginia Tech, in a (graduate!) surface chemistry course!

    [Do not make the mistake of experimenting indoors. The solution takes rather a lot of rinsing to remove it from floors, and a large bubble can cover an amazing amount of floor when it bursts. DAMHIKT.]

  8. David Marjanović says

    In fact you are conducting experiments which will reveal the insidious truth about the effects of bubble bath on young, vulnerable minds.

    …Well, that, too.

    We discovered that soap bubbles last for days when you make them at -25F. When they hit the snow, some of them crack open like eggs.

    Awesome.

    DAMHIKT.

    ?

  9. ChasCPeterson says

    PZ: I don’t know from Pixelink, but if it will save as a .jpg file, you just open the .jpg from ImageJ. Probably will open other formats too; I never tried. But I don’t know from Pixelink.

  10. says

    Pixelink makes very nice and relatively high end cameras specifically for microscopy. They can save images in a number of formats (I’d rather use something lossless, not jpg), but the annoyance is having to shuffle between two different programs. ImageJ does everything I want except image capture; the Pixelink µScope software is kind of minimalist, and also only works on PCs.

    It’s particularly annoying if I’m doing timelapse and acquiring lots and lots of images, all of which have to be processed and analyzed similarly. I’m probably going to have to invest some time this summer doing scripting to make it all work.

  11. bodach says

    Where do you get Discovery Institute water? I’m near Seattle but afraid to get too close to them…

  12. Rich Woods says

    If it’s a combination that works on a Mac so I can ditch the ugly little PC in my lab that does nothing but image capture

    More than two decades ago, this situation was reversed. Just goes to show how it can all come down to the breadth of hardware support and to practical software rather than fan love/hate.

  13. Rich Woods says

    @nonnotthatla #7:

    Reminds me of our 3-winter sojourn in Cloquet, MN, several years ago.

    I have to ask, but was that three winters in a single year?

  14. gussnarp says

    Thank you for the inspiration. It’s finally gotten warm enough to really enjoy playing outside, so I’ll be making bubbles with the kids this weekend.