Pupils use a rapid method to render the bacterium Escherichia coli "competent" in order to uptake plasmid DNA. They also have growth on the plain LB plates by the untransformed cells (which serve as controls). Students perform a cell resuspension from the transformed and untransformed colonies, followed by a plasmid minipreparation on those cells, to enable them to demonstrate that only transformed cells have the plasmid present.