Investigating the effect of air flow on evaporation

Assessment focuses

AF3, AF4, AF5

Context

Templates for a set of three investigations on evaporation were provided. The independent variables for these investigations were temperature, surface area and air flow. The pupils were allowed to choose one of these, and the class compared the results afterwards.

Luke's group decided to investigate the effect of air flow. The teacher suggested some locations that may have different air flows, and the group made their plans and gathered data.

The evidence

A child's handwritten work on an 'Evaporation' template.

The title of the template is 'Evaporation. At the top of the page this content appears: 'Name: Luke'. The template contains eight headings, and a child has written under seven of them. The Question: Does airflow effect the rate of evaporation? Our plan Get two papper towels and put one in each tray and get them wet and see witch one drys quicker What we are changing (our variable) Airflow What we are keeping the same A amount of water, amount of time, some size and shape. What we are measuring Volume of water after we sqeeze the paper towels Our equipment paper towel (2x) fan (1x) 10ml of water (1x) stop watch My prediction (with reasons) I think the paper towel with no wind would dry quicker because it doesn't have wind blowing on it and the wind might keep some. Now, on another piece of paper, draw a table in which you can record your results as you collect them.  

A child's hand-drawn graph showing the air flow of different paper towels.

The horizontal or x axis is labelled with 'paper towels'. The vertical or y axis is labelled with 'time in mins'. The following results are recorded: A equals 10 mins B equals 155 mins Underneath the graph the child has written: A= with wind flow B = without wind flow

Teacher's notes

After watching other pupils, Luke's group changed their minds about how they would carry out the investigation. It is because of this original plan that he writes about measuring the volume of water to be squeezed out of the paper towels (the dependent variable). During discussion, Luke's group said that the paper towel with the faster airflow dried much quicker.

Next steps

  • Discussion of the difficulty in controlling certain variables, with the idea that changing the location potentially changes more than just the air flow.
  • Consideration of improvements to working methods to provide quantitative measurement of air flow, such as using a fan on different settings.

Assessment commentary

Luke did not produce a table but he shows that he can present data using a simple bar chart. He makes reliable and relevant observations. He identifies straightforward patterns, and gives a simple description of what happened, with a brief spoken group conclusion.