Here's how to estimate the size of an oil molecule just using water and an oil drop: https://spark.iop.org/estimating-size-molecule-using-oil-film https://spark

Here's how to estimate the size of an oil molecule just using water and an oil drop: https://spark.iop.org/estimating-size-molecule-using-oil-film https://spark.iop.org/estimating-size-molecule-using-oil-fil... (They use some other stuff, but you get the idea) You can back out Avogadro constant starting with this experiment.