The past few years in the school where I preciously taught 4th grade the classes all got together and we had a lesson dealing with estimation, mean, median, and mode.
Students would estimate the following: weight of the pumpkin in pounds, how many lines, circumference of the pumpkin, as well as the number of seeds.
Prior to the students estimating the weight we would number and weigh each pumpkin prior to the students estimating.
Last year all 4 classes entered their data into a Google sheet the data for each pumpkin. The great thing about a spreadsheet on Google is that you can all share the same sheet and enter the data in as you get it. The sheet has the formulas in it for you already. Click here for a copy of the sheet. Remember, if you are going to do this as a whole grade - make sure you are all using the same sheet.
Below is a GIF showing how what the sheet looks like when you enter the data followed by a short video on YouTube with audio.
Any questions please let me know!