Today students participated in a cell membrane activity. We first reviewed what the cell theory is which states that all living things are made up of cells. Next we talked about our two new words: Cell membrane and cytoplasm. Next we made a model of the cell membrane and cytoplasm. Students watched as the white cornstarch turned purple and the orange Lugols stayed orange. We then discussed the possibilities of why this happened. Finally, we found out that only the orange molecules can travel through the bag(cell membrane) while the white cornstarch molecules were too large to go through the bag. This represents how the cell membrane works. It protects the cell by allowing some molecules to cross the membrane and keeps other things out.