Last week in Junior ELP Science we learned all about the properties of water that were related to the measurement of temperature and the specific temperatures that water froze (turned into ice) and boiled (turned into steam). We discovered that water freezes at 0 degrees C and that it boils at 100 degrees C. We also were able to give everyday examples of these things happening (ice cubes in a freezer, snow on the ground, kettles boiling). We got experience using a thermometer and we made a big effort to learn that special word so that we could use it in everyday life.
This week our experiments are going to take us down to the River Forth…where we can compare salty seawater with water from the taps in the school and our homes. What differences will there be? How can we make measurements of these differences? And could we turn seawater into water more ready for drinking or washing?
After an introductory chat about what we already knew about water from the sea we discovered that we were already to express in our own words that it was
With a bit of further questioning, using specific past experiences and AifL techniques to support the assessment of prior knowledge, we were also able to ascertain that the water in the River Forth is SALTY.
Our lessons this week would go on to concentrate on the saltiness and dirtiness of the water from the Forth.
Using the sheets attached at the top of this page we further explored the world of sea water and salt. We first watched a video about salty water and discovered that people can take the salt out of it! This was a difficult thing to imagine – after all salt seems to “fade away” or disappear in water when we add it, doesn’t it?
Using the examples we saw on the video we discussed how we might get salt from water in the River Forth. Mr Kidd had collected a bottle of sea water from behind Cockenzie Power Station and we had a good look at it while we thought about the job in hand.
The water from Cockenzie was colourless and clear like tap water but there were one or two important differences. One of these was obvious immediately to everyone. There were “black bits” floating in the bottle! (Yuck!) Less obvious was the fact the water was salty but we decided this must be the case because of past experiences some of us had had paddling in the sea. But how could we prove it? And could we make the water cleaner as well as unsalted?
Referring to what had been done on the video and using the techniques described in the worksheets we set about trying to make fresh water from salty water.
This was good fun, though we had to be careful when boiling the hot sea water – as we were about to find out that sea water can spit!
We boiled the water until all of it disappeared as steam into the air. We were left with a white powder that looked suspiciously like table salt. We got some table salt to do a visual comparison. Then Mr Evans appeared with a box that looked a little like this…
Inside it was proper Prestonpans Sea Salt – and it looked exactly like ours!
We then discovered that in the past the River Forth around this area was responsible for all of the salt used in Edinburgh and its surrounds. Edinburgh’s salt came from pans at Prestoun. Today it is known as ‘Prestonpans’ as a reminder of how salt was produced in the past. Prestonpans, of course, is where our school is and where many of us have lived for all our lives. The salt was also imported to other faraway places such as Scandinavia and the Baltic.
Here is a mural of Prestonpans Saltworks.
This was the last ever saltworks in Scotland. It was on the seashore, and originally, like many others, made salt by evaporating seawater in large iron pans. Latterly the pan was used for refining rock salt, which ended in about 1959.
This view shows the front of the works, which was demolished in 1978. The buildings seen here were probably warehouses. The works was used for packaging salt until the early 1970s. Many of your parents may have been born about that time but your grandparents may remember the salt works – why not ask them?
We had great fun discovering that we could take salt out of sea water and through filtering (see “Dirty water” file) , we could take out lots of the dirt. By the end of these lessons we were proper water scientists – but we were all fully fledged Panners in every sense of the word!