We have been exploring the action of forces in everyday situations and we have found out that nothing much would happen without them. Today we explored forces a bit further, and in doing so we learned a little about conducting an experiement that was a “fair test”. We wanted to know how far a toy car would travel after going down a ramp so first we tried this simulated experiment . We noticed that in this experiment, there were two variables, and that two tables of results were completed. It was then possible to compare the two tables.

In our experiment, there were a number of variables. These included:

• the type of car
• the tilt of the ramp
• the surface of the ramp
• the surface of the floor
• the release point
• the method of release

We knew that to conduct a fair test, we should only change one variable at a time. One group kept the same ramp tilted to the same height and tested a number of different cars on it. Another group used two different ramps and compared the results they recorded for each when they adjusted them to three different heights. Most groups used one car and tested how far it travelled when released on each of 6 different ramps, one covered in carpet, one in corrugated cardboard, one in plastic, one in synthetic turf, one in sandpaper and one smooth masonite.

The important lesson of the day was that if you change more than one variable at a time, there is no way of knowing which one affected the outcome.