This study found that “embedded letters were mastered in fewer trials, were less frequently confused with other letters, were remembered better 1 week later, and facilitated performance in word reading and spelling transfer tasks compared to control letters. We suggest that embedded mnemonics better secured letters to their sounds in memory which in turn improved word learning for children in Ehri’s (2005) partial alphabetic phase.” – Adina Schmidman & Linnea Ehri – Embedded Picture Mnemonics to Learn Letters

Another study revealed that children taught with the embedded picture mnemonics learned more letter name associations than did the control group. The embedded picture mnemonic had a positive effect on long term memory reflecting an increase from a moderate effect sizes for letter naming (d = .69) on the first week post test to a large effect size for letter naming (d =1.12) on the second week post test. – THE EFFECTS OF MNEMONICS ON LETTER RECOGNITION AND LETTER SOUND ACQUISITION OF AT-RISK KINDERGARTEN STUDENTS

But when it comes to teaching letters and sounds, no question about it, use embedded mnemonics. They work. – Timothy Shanahan