500
Place the comma(s):
Mr. Green Ms. Seavey and Ms. Bicknell teach English 9 on odd days and Ms. Waterfall Ms. MacLean and Ms. Nelson teach English 9 on even days.
Mr. Green, Ms. Seavey, and Ms. Bicknell teach English 9 on odd days, and Ms. Waterfall, Ms. MacLean, and Ms. Nelson teach English 9 on even days.