1. Conclusions

2.  At the end of a successful experiment, the experimenter should be able to form some conclusions about what was observed.

3. Conclusions  All conclusions should do three things:  Summarize what was discovered (one sentence).  State your specific results (include specific numbers or details your observations).  Refer back to your hypothesis. Was it correct?  More advanced conclusions may also:  Discuss one’s level of confidence in their conclusion based on the sources of error they have identified.

4. Example  Mrs. Posca tested the effect of the amount of chocolate chips in cookies vs. How many were eaten per day.  She predicted that her kids wouldn’t like all the sugar, so more chocolately cookies would be eaten less. Her observations are below: Cups of Chocolate Chips# of Cookies Eaten 14 26 37 410

5. Example  What would be an appropriate conclusion for Mrs. Posca to make?  More chocolate chips in the cookies increases the number of cookies eaten.  Only 4 of the cookies with the least chocolate chips were eaten compared to 10 of the cookies with the most chocolate chips.  Her hypothesis that fewer chocolaty cookies would be eaten was incorrect. This could be because kids actually like sugar.

6. Sources of Error  Another part of a scientist’s analysis involves considering an experiment’s sources of error.  This is where the scientist discusses other factors that may have affected the outcome of the experiment.

7. Sources of Error  A source of error should NOT be a mistake made by the experimenter.  Ex: I spilled the chemicals.  Ex: I measured the length wrong.  It should be something that was difficult to control or account for while executing the PROCEDURE.  It should be relevant and plausible.

8. Examples  Good sources of error:  It was difficult to keep each trial the same because...  The measuring device is difficult to hold/use/read precisely.  Contamination or lack of 100% clean equipment.  Bad sources of error:  I broke the glassware.  I wrote down the wrong numbers.  Godzilla stepped on my experiment.