We wanted to investigate which edible liquids decay teeth the quickest. We split into 15 pairs of children and each covered a hard boiled egg with a different liquid, whilst ensuring various conditions remained the same, i.e. the size of the egg, volume of liquid, location of eggs etc. Then we made predictions as to which egg we thought would decay the quickest, with cola being the top decaying 'agent' prediction and milk the lowest.  Then we sealed our eggs and we will observe over time.