Rhyming is SO important to practice with your 3,4, and 5 year olds. It is the #1 phonemic awareness skill- the "easiest" to master and a huge predictor in phonemic awareness.
Phonological/Phonemic Awareness is essential for reading. Phonemic awareness is the process of identifying and manipulating sounds of spoken language.
Try asking your young readers to rhyme words with pig, rock, tap, or ran. It's common for 4 year olds to name a word with the same beginning sound, but remind them we are looking for words with the same ending sounds.
If your reader can rhyme, ask them to listen to a few CVC words you say and to tell you how many sounds they hear. This is phoneme counting and is also very helpful in learning to read!