Don't start with the whole word. Start with the beats.

Cat is one clap. Sun-shine is two. Am-i-ri-yah is four.

Clap the parts. Say the parts. Then say the whole word.

Same trick with meaning. Help is the root of helpful. Joy is the root of joyful. If she hears the root, she can guess the word.

Repeat until it is boring. Boring is how it sticks.