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I live near a fresh-water lake in the middle of Europe, and decided to do this experiment with my kids a few years back .. we took a jar, scooped up some water,

I live near a fresh-water lake in the middle of Europe, and decided to do this experiment with my kids a few years back .. we took a jar, scooped up some water, threw a couple small bits of algae in, and took it back to our kitchen, where we watched it daily for months. It was extraordinary to see things growing right away .. the kids loved getting up and checking on 'the critters and the goop', as we called it. Our patience was rewarded when I spotted a tiny hydra had attached itself to the side of the jar .. https://en.wikipedia.org/wiki/Hydra_(genus) https://en.wikipedia.org/wiki/Hydra_(genus) We watched it grow and grew, going from near-microscopic to the size of one of the kids finger nails, turning a deep and vibrant red as it aged. There were lots of other things too, which we never got quite around to naming .. freshwater shrimps, a couple of tiny fish (which didn't survive a heat-wave also, alas) .. but eventually it became a murky mess, and we cleaned the jar out for other experiments. This is a really neat way to teach kids about life, in my opinion. The next time we do it, we'll rig up a USB microscope and have it pointed into the depths - I have a feeling that my kids are going to find operating the microscope far more intriguing than any video game. Would be grand to discover there's a microscope out there that can be remotely moved .. we may have to cannibalise a 'light following flower robot' to rig up our own "Exploratorium"™ .. ;)

jfk13 7y ago
I remember doing this as a child; I had a microscope, so it was awesome to put a drop of this water on a slide and watch all the tiny organisms moving around. The smell did get a bit overwhelming after a while, though...
- DanBC 7y ago
  If you have a group of children you can make a microscope out of a low power laser pointer, a syringe, a wall, and something to hold it all together. https://www.youtube.com/watch?v=_fHSys_pIEA https://www.youtube.com/watch?v=_fHSys_pIEA
leggomylibro 7y ago
We did a variation on this in science class as kids, which our teacher called a "slice of life". Basically you take two sheets of transparent nylon and bolt a U-shaped rubber or nylon tube in between them such that the two sheets flex outwards in the middle in a pouch shape. Then you stand it up so that the opening faces up, and pour the water in. If it leaks, you might need to space the bolts closer together or add some sealant. And you'll probably also need to make some stands to go on either end and keep it upright. The curved nylon sheets act as lenses which magnify the pond life a bit - just be careful if you have pets.
- Terr_ 7y ago
  > The curved nylon sheets act as lenses which magnify the pond life a bit - just be careful if you have pets. And if it makes a good lens, don't burn your house down by accident by leaving it in a sunny patch.
tzs 7y ago
Another good one, to teach about how there is microscopic life all around us, is to make sourdough bread using wild yeast and bacteria. Starting with just flour and water, you can capture the wild yeast and lactobacilli that are floating around your kitchen and cultivate them in a ball of dough. You can establish a colony in such a dough ball that can last centuries [1], breaking off some of it whenever you want to make some bread. Sourdough bread made from your colony might taste a little different than sourdough bread made from someone else's colony, because different places have different subsets of the something like 20 species of yeast and 180 species of lactobacillus there are, and different species can have different flavor. [1] Boudin Bakery in San Francisco is still using the colony it started in 1849.
- xattt 7y ago
  Sullivan Street Bakery cookbook suggests the use of washings of fruit or veggies that have bloom on them to kick-start the process. There’s definitely a pungent period during the initial start where you second-guess yourself if you’ll be eating this.
- dnhz 7y ago
  Check this out: http://www.thefreshloaf.com/node/37259/mythbusters-grain-yeast-or-air-yeast http://www.thefreshloaf.com/node/37259/mythbusters-grain-yea... It seems like the source of microorganisms is from the input grain itself, not what's in the air.
- fit2rule 7y ago
  Yes, we have a sour-dough yeast colony already, refer to it often .. Another good one is miso.

jfk13 7y ago

I remember doing this as a child; I had a microscope, so it was awesome to put a drop of this water on a slide and watch all the tiny organisms moving around. The smell did get a bit overwhelming after a while, though...

DanBC 7y ago
If you have a group of children you can make a microscope out of a low power laser pointer, a syringe, a wall, and something to hold it all together. https://www.youtube.com/watch?v=_fHSys_pIEA https://www.youtube.com/watch?v=_fHSys_pIEA

leggomylibro 7y ago

We did a variation on this in science class as kids, which our teacher called a "slice of life". Basically you take two sheets of transparent nylon and bolt a U-shaped rubber or nylon tube in between them such that the two sheets flex outwards in the middle in a pouch shape. Then you stand it up so that the opening faces up, and pour the water in. If it leaks, you might need to space the bolts closer together or add some sealant. And you'll probably also need to make some stands to go on either end and keep it upright. The curved nylon sheets act as lenses which magnify the pond life a bit - just be careful if you have pets.

Terr_ 7y ago
> The curved nylon sheets act as lenses which magnify the pond life a bit - just be careful if you have pets. And if it makes a good lens, don't burn your house down by accident by leaving it in a sunny patch.

tzs 7y ago

Another good one, to teach about how there is microscopic life all around us, is to make sourdough bread using wild yeast and bacteria. Starting with just flour and water, you can capture the wild yeast and lactobacilli that are floating around your kitchen and cultivate them in a ball of dough. You can establish a colony in such a dough ball that can last centuries [1], breaking off some of it whenever you want to make some bread. Sourdough bread made from your colony might taste a little different than sourdough bread made from someone else's colony, because different places have different subsets of the something like 20 species of yeast and 180 species of lactobacillus there are, and different species can have different flavor. [1] Boudin Bakery in San Francisco is still using the colony it started in 1849.

xattt 7y ago
Sullivan Street Bakery cookbook suggests the use of washings of fruit or veggies that have bloom on them to kick-start the process. There’s definitely a pungent period during the initial start where you second-guess yourself if you’ll be eating this.
dnhz 7y ago
Check this out: http://www.thefreshloaf.com/node/37259/mythbusters-grain-yeast-or-air-yeast http://www.thefreshloaf.com/node/37259/mythbusters-grain-yea... It seems like the source of microorganisms is from the input grain itself, not what's in the air.
fit2rule 7y ago
Yes, we have a sour-dough yeast colony already, refer to it often .. Another good one is miso.