Wednesday’s Nor’easter provided Sue with an opportunity to use snow in the eighth grade’s investigation of the atmosphere and weather. She asked the students to think about how many inches of rain we would have gotten if it had not been cold enough for snow, inciting curiosity about the relationship between liquid water (rain) and frozen water (snow). The class then discussed how they could determine how much water was in snow.
They decided they would measure the height of a beaker and fill it with snow, then allow it to melt and compare the height of the snow to the height of the meltwater. Sue had them hypothesize about the results. Some students thought that the beaker might overflow, while others were convinced that the snow would reduce into a smaller volume of water. Sue also asked the students to think about the experimental design. They would make sure to not pack down the snow during collection by pushing the beaker into snow until the bottom rested against the top of the snow, then sliding a clipboard under the beaker to hold snow in when inverting. They also decided to place something on top of the beaker during the melting process to make sure that no water escaped via evaporation. Finally, both classes would collect snow samples of the same size so melting results could be compared.
The entire class then trudged outside in the cold to collect the snow samples. Sue had on appropriate gear, so she did most of the collection work, with the help of one or two eager students who had worn their snowboots to class. Because the eighth grade classes are in the morning on Thursdays, Sue and I were able to watch the beakers of snow melt during the rest of the day. I took pictures roughly every hour so the students could review what had happened while they were not in science class. Below is the melting experiment photo-timeseries:
10:45am Note the line of saturation in the snowpack and the lack of pooled meltwater.
11:30am Pooled meltwater present.
2:20pm Completely melted, about 300mL of water.
Because this snow experiment and the photo-timeline were conceived somewhat on-the-fly, there is room for evolution and improvement. The experiment was enhanced with the second class, who collected snow samples of different sizes (smaller than, same as, and larger than that of the first class) to compare the ratio of snow height to meltwater height. Volume of snow could be compared instead of height. In terms of photo-documentation of the melting process, we decided to take pictures after the snow had partially melted. It would be better to have a picture of the initial volume or height of snow. It would also be better to turn the beaker such that the volume scale is shown in the photographs or include a ruler for scale reference.
There’s more snow in the forecast soon…who’s up for some snow experiments?