Tell the pupils to: a) describe what is happening to each egg. b) calculate the percentage mass change c) draw a graph of class average results.
Step 2: Dissolve the egg shells
Place each of the eggs into a 250ml beaker and cover with vinegar. Place them in a spot where they wont be tampered with, (then put them somewhere even safer with a note on them, saying "do not touch"). Leave for 2-3 days (over weekend is best, you can set them up on a Friday lesson and revisit Monday/Tuesdayish.