Predict, Observe, Explain – Sedimentation

by Deb on April 23, 2010

The big girl has been asking to do another one where we ‘draw what we can see’ so we did an experiment on sedimentation.  But this time we played  with the new toy and recorded her doing the experiment so you can see how easy it is.  Sedimentation is about how rocks and sand settle out in water, so all you have to do is put rocks and sand into a jar with water, shake them up and let them settle.

I have to confess we did this a few times to get the video, hence the outfit changes, but you can still see how easy it was – it was the videoing that needed practice, not the experiment.

We’ve never even talked about this sort of thing before so I was interested to hear what her predictions would be like.  Interestingly, they were fairly similar to what teenagers come up with, involving rocks at the bottom.

Jars with settled sediment

In the end it isn’t quite correct but she was fascinated by the layers that formed.  Especially because there was a black layer, but nothing we put in had black in it – she spent a bit of time looking around the garden deciding it must be all mixed up.

Closeup of sediment layers

I’ve always taught in the outback, so I’d love to try this with soil or beach sand.  We get very clearly defined layers with the quartz grains at the bottom and the clay at the top, there’s very little organic matter and it’s similar to genuine streambeds.  If anyone else who has different types of sand and soil tries this, please let me know what happens!

And just to be like the professionals, here are some of the out-takes.

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{ 7 comments… read them below or add one }

Chris April 23, 2010 at 8:00 am

OO!

I’m so trying this with my boy this weekend 🙂 except he’ll probably get carried away with the shaking!

another great idea, thanks!
.-= Chris´s last blog ..Happy Easter! =-.

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sally April 23, 2010 at 12:16 pm

Sounds great. Does it matter what you put into the jar, I’m thinking rocks, sand from the sandpit, but not sure what to use as the last one.
Oh and by the way, you are awesome and my hero at the moment.

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Deb April 23, 2010 at 1:25 pm

Wow, thankyou, I’m honoured. I’ve always done it with the sand around us and it’s worked, but if you had something like plain beach sand that wouldn’t be very interesting. Most natural sands in Australia are mixed and will give you layers, if you’re really desparate you could even add something like talcum powder to get a fine layer at the top. Crushed kitty litter or chalk would work as well, and sidewalk chalk would give you some great colours.

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Ro April 23, 2010 at 3:17 pm

Love these type of experiments 🙂
Saw a similar one recently on the telly where they put the drink bottle in the spokes of a bicycle wheel and the water became (almost) crystal clear after a few times around the block lol.
.-= Ro´s last blog ..Start floggin =-.

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Hear Mum Roar April 24, 2010 at 11:06 pm

I think my nine year old would love this. I’d like to see what would happen if you did it with compost.
.-= Hear Mum Roar´s last blog ..Happy birthday, fairy girl! =-.

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Annette April 25, 2010 at 7:37 am

What a wonderful and simple experiment – will have to do this one!
.-= Annette´s last blog ..My gardening wall of shame! =-.

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Emily January 5, 2011 at 10:06 am

My 10 year old daughter and I tried this with a mix of gravel, sand, potting soil and regular dirt for a science fair project. Our top layer was also black. We had three other layers.

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