Summary Look at cheek cells stained with methylene blue, or iodine, under the transmission microscope. Science content Biology: Features, Adaptations of Living Things (K, 1, 3, 7) Biology: Sensing, Organ Systems (4, 5, 6) Lessons activity is in DNA extraction from cheek cells Materials non-pointy toothpick for each student glass slide and cover slip for each student methylene blue, 1% (0.5% in some fish medicines works great). If not available use tincture of iodine, from the drug store microscope, ideally with a 40X lens Procedure Students add a drop of methylene blue (or iodine to a slide). Students scrape cheek cells from the inside of their cheeks with a toothpick, then wriggle them off in the drop on the glass slide. Drop on a cover slip. Look at the cheek cells under low power to start to find the cells. Then increase the power, keeping a good-looking cell in the centre when moving up to the highest power. Look for the nucleus in the centre of the cell. With methylene blue, other cell organelles are also visible, and sometimes bacteria (dark blue spots outside the cheek cells). Notes Primary students, and many intermediates, need a strong teacher presence around the microscope. Grades taught Gr 1 Gr 2 Gr 3 Gr 4 Gr 5 Gr 6 Gr 7
