Mnemonic schemes are often used to help us remember various things

Mnemonic schemes are often used to help us remember various things. You know the "thirty days has September" scheme. A researcher wants to investigate the use of mnemonic schemes in the learning of lists of words. Participants will be trained to use a rhyming scheme to learn one list, an imagery scheme to learn another list, and no scheme to learn yet another list. She hypothesizes that the imagery scheme will produce the fastest learning, and no scheme will produce the slowest learning. Which design (i.e., within participants or between participants) should she use and why?