The objectives of our lesson on "materials and their properties" were:
* to plan a fair test
* to make and record measurements of time and volume of water
* to use the results to make comparisons and draw and explain conclusions.
We set out to determine the "porosity" of different soil samples - gravel, soil, sand and mixtures. The children had discussed what made a fair test and picked their equipment, which included calibrated measuring jugs, same-sized funnels, same-sized filter papers, calibrated receiver containers, the same amount of water and stopwatches.
Each group (of mixed ability) had the four samples. The task was to find which sample was the most porous or which soil type allowed the water to pass through quickest. Other unspecified objectives were: following instructions, control in experimentation, how to interpret results and collaborative learning.
The children went about their tasks enthusiastically and I was optimistic.
But this turned to caution, then panic and bewilderment at the results because many of them had poured their water down the back of the filter paper, which falsified their figures. This led to a class discussion when the pupils compared each other's results and worked out what had gone wrong.
We then successfully repeated the experiment. They discovered the water took a similar amount of time to pass through samples of the same type and, when they compared results, the children knew they must have done the investigation correctly. This boosted the confidence of those with low self-esteem.
The noise level at times was deafening but as I wandered around asking the children questions, I realised they were all on task and learning.
As time is often short, you may not be able to repeat the experiment. I suggest you prepare by showing them which side of the filter paper the water needs to be poured down. And make sure those children who enjoy a race do not start scraping out their soil samples just to be first
Sue McKinney teaches at Granard Primary in Putney, London