I came downstairs this morning to find Bean 9 conducting an experiment in the kitchen. Inspired by an online competition to design a tool for survival on a desert island (Year of Engineeering challenge), she was attempting, with the use of a filter constructed from paper, to desalinate a salty water mixture. Unfortunately her attempt was unsuccessful (see this post about the Importance of Failure), but it did give us the idea of trying to extract pure water from the sea.
We’d planned a morning trip to the beach and so after building our castle:
we collected a sample of sea water:
On arriving home, a plan was hatched. Here is how we converted this muddy concoction into pure drinking water:
1. Let the sample settle for an hour, allowing sand and other large material to fall to the bottom of the box:
2. Strain the sample through the finest sieve in the kitchen:
3. Filter the sample through a sand filter, in this case an old Brita water filter (perhaps next time we might design our own!):
4. Boil the sample to destroy any bacteria that might have been present.
5. Condense the sample, by collecting the steam that is given off from the boiling process and then cooling it down. To do this we created our own simple distillation equipment:
Here is Bean 9 to explain how it works:
6. Cool the now pure water in the fridge and drink!
And there you have a simple hands on science activity to complete with your kids after a visit to the beach (if you have the energy after all that digging!).