Ketchup as a kitchen cleaner?

Following their coin treasure hunt yesterday, Year 1 worked in teams and conducted an experiment to find out which substance cleaned their treasure the best; Ketchup, lemon juice or coke.  They had to decide what their hypothesis was  going to be (I think……..will clean the coins best) and then fill out a chart with their observations each time they used a different liquid.  The result was that ketchup cleaned the tarnished booty the best!