Which Magnet is the Strongest?

This week we are developing investigations to determine which out of 4 magnets is in fact the strongest. I gave students a list of materials including:

100 paper clips
4 magents: ring magnet, wide bar magnet, wand magnet and horseshoe magnet
data table
pencil

With a partner, I then asked them to develop an experiment that would help them determine which magnet was the strongest. They could collect qualitative or qualitative data based on their experiments. They were required to write a procedure, collect data and then come and share it with the class at the end of the 2nd class period. Here are some of the procedures the students wrote:

Based on their data, none of the classes were able to definitely tell me which magnet was the strongest. Some groups said their data was too close between magnets, whereas other groups felt that because the decision wasn't unanimous that this data wasn't accurate and therefore we needed to conduct a fair test that everyone could do. They felt that if the data had similar patterns for the same test then they could better determine which magnet was the strongest.

The next two class periods were used writing and conducting a fair test using the same procedure amongst all six classes. The students spent a lot of time trying to get rid of as much human error as possible. This included:

how they held the magnet
how long they held it in the pile of paper clips
if paper clips fell while picking the magnet, did it count
how many trials we should conduct
do we include magnets that seem to have demagnetized
do we total the number of paper clips or just compare trials

This detailed reflection and careful thought process shows the growth our young scientist are making in the world of developing a fair test! I am so proud of all of them!!!