How large are Cells?
How would you sort a protein, a cell, a grain of sand, and an atom by size? Start with the smallest structure.
Atom < Protein < Grain of Sand < Cell
Bird eggs are the largest (egg) cells and are even visible to the naked eye. Therefore, cells can indeed be larger than grains of sand.
A study investigated students' perceptions of the size of cells [1]. The results indicated that they had difficulties accurately estimating cell sizes, presumably because most cells are only visible with a microscope.
In another exploratory study involving biology students, a similar issue was examined [2]. Out of ten surveyed students, five believed that a grain of sand was larger than a cell because a grain of sand can be seen with the naked eye [3]. Only two students were aware of the diversity of cells [4].
Sources
[1] Dreyfus, Amos / Jungwirth, Ehud: The pupil and the living cell: a taxonomy of dysfunctional ideas about an abstract idea. Journal of Biological Education, 23:1, 1989, p. 49-55.
[2] Knox, Milissa: Thinking Beyond the Fried Egg Model: How Accurately Do Students Perceive Cells in a Living Context? Electronic Theses and Dissertations. 2355. 2015, p. 47.
[3] Ibid., p. 85.
[4] Ibid., p. 85-86.