Onset rimes are composed of two parts. The onset is the beginning sound that can be heard when words are sounded out. The rime is the part of the word that is left after the onset is removed. When the two parts are separated, it is called onset-rime segmentation.

One-Letter Onsets

One-letter onsets are not blends or chunks, but they are single letters at the beginning of a rime. One-letter onsets are a single syllable. The “c” in cat is a one-letter onset, as well as the “h” in house. The letter stands alone from the rest of the rime. A list of common word families that occur in the one-letter onset-rime group is: best, head, light, sink, tick, coat, tub, bug, hand and pail. Removing the one-letter onset you can create another one-letter onset-rime or if you add a blend, then you will have used a two-letter onset.

Two-Letter Onsets

Two-letter onsets are made up of blends that typically start a sentence. A blend is when two syllables come together to make a new sound different from the original sound. The English language has 35 double letter blends. A list of blends that make up some of the two-letter onsets: ch, tr, sh, th, bl, pl, sn, th, br and pr. With an onset rime such as bread, the onset rime is the “br.”

Onset-Rime Segmentation

It is important to classify the difference between a two-letter onset and a one-letter onset when it is time to segment. Teachers use segmentation to help students to build rhyming words and patterns. The teacher will model removing the onset and say the remaining rime. When students add another onset to the rime, they have created a rhyming pair. For example if a teacher says, "dog." She would drop off the "d" and be left with "og." When the students add "fr" and say the word, "frog," they have found a pair of rhyming words. It is an important early reading skill for children to be able to segment onset rimes. When children have difficulty segmenting the onset rimes, they often have trouble learning to read later.

Activities Based on Onset Rimes

Within a classroom, a teacher can use her pocket chart to play a game with her students. She can write out several words and ask the students what part she will need to remove to create new rhymes. When they tell her to remove the onset, she can cut off the first letter. She then can place the rime into the pocket chart and ask students to write out new onsets to create rhyming words with the original onset-rime. The book “Andy, That’s My Name” by Tomie dePaola is a good way to introduce onset rimes, as the characters build words with Andy’s name.