Pencaitland Primary Blog

Our project on solids, liquids and gases continued today with more experiments.  We discovered how to use a filter to separate solids from liquids. We mixed flour with water to make a cloudy ’suspension’ which we thought looked like a banana milkshake. Mr Cain challenged us to produce clear water from this milky white liquid! We discovered that if we used a funnel and coffee filter paper we could produce water that was clearer, but still a bit cloudy.  We then used the funnel and the same filter paper and the second time around it produced much clearer water. We had learned that the water runs quickly through the filter trapping most of the solid particles, but some small particles pass through.  As a result the filtered water in the first beaker was slightly hazy.  Water then passes more slowly as the filter holes get blocked and so even small particles can’t pass through and the water is clearer.

As a class we also made a filter bed, with sand, gravel and pebbles and succeeded in producing very clear water very dirty, muddy water.