Two suggestions here:
1) Don't require all 900 seconds of data for in-lab users. For example, if a student thinks they have enough data on the freezing portion of the cooling curve after 11 minutes, allow only 660 seconds of data total to be put in. Have the report ask for the time of the final data point before students have to put in their data, and build the data table based on that value. This became an important issue because I am splitting my 2 hour 50 minute lab period into two 75 minute sessions so that all my students can get lab experience each week. Trying to get two 15 minute data collection runs into 75 minutes, when you have to wait for water to heat up also, did not work very well. If the data collection could be cut shorter based on how it's looking in lab, that would help a lot.
For those completing the experiment online, it's fine to have the generated data set go to 900 seconds, so no need to reprogram that.
2) Allow earlier times for the "Final Time to Include in the Cooling Portion". The current minimum time is 300 seconds, but several of my students had samples that switched from cooling to freezing at an earlier time, such as 240 or 270 seconds. Consequently, the fit to their cooling region, which was forced to go to 300 seconds by the report, did not have a great R^2. Although it probably had little effect on the freezing point determined, I suggest allowing that parameter to go down to 200 seconds.
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