Did you know that just four prefixes account for 97% of all prefixed words students encounter in school texts? According to Honig et al. (2013), teaching a small set of high-frequency affixes can have an outsized impact on vocabulary growth, especially for students who struggle with decoding or deriving meaning from unfamiliar words.
For SLPs looking to work smarter (not harder), morphology instruction is a powerful way to boost comprehension, vocabulary, and language flexibility across grade levels.
In this post, we’ll walk through evidence-based, student-friendly strategies for teaching prefixes, suffixes, and root words in your speech therapy sessions.
Why Morphology Matters
Research consistently shows that explicit morphology instruction helps students:
✔️ Increase vocabulary knowledge
✔️ Improve decoding and spelling
✔️ Strengthen reading comprehension
✔️ Make meaning-based connections across content areas
Carlisle (2010) notes that teaching students how to analyze word structure equips them to infer meaning, even when encountering completely new words. This skill makes morphology one of the most efficient vocabulary interventions SLPs can deliver.
Step 1: Teach What Affixes Are and How They Change Meaning
Before diving into lists of words or graphic organizers, start by building conceptual awareness. Students benefit from clear, concrete examples of how affixes transform base words.
For example:
✔️ cat → cats (adding -s means more than one)
✔️ happy → unhappy (un- changes the meaning to its opposite)
This explicit comparison helps students understand that:
1️⃣ Words are made of meaningful parts
2️⃣ Those parts carry clues
3️⃣ We can use those clues to figure out meaning
This aligns with research indicating that metalinguistic awareness (thinking about how language works) supports later vocabulary growth (Kieffer & Lesaux, 2008).
Step 2: Explicitly Teach High-Value Prefixes and Suffixes
Rather than overwhelming students with dozens of affixes, focus on the ones they’ll encounter most often.
According to Honig et al. (2013), the most frequent prefixes include:
✔️ un-
✔️ re-
✔️ in-/im-
✔️ dis-
Introduce each prefix with:
✔️ A student-friendly definition
✔️ An icon or visual
✔️ A few high-frequency examples
If you’re an SLP Now member, you can use the Prefixes & Suffixes Skill Packs, which include definition cards, visuals, and examples that make instruction simple and consistent.
Not a member yet? You can sign up for a free trial at slpnow.com/trial and download the skill packs!
Give students printed cards so they can collect, sort, and reference them across sessions, almost like vocabulary “trading cards.”
Step 3: Teach Students to Become Word Detectives
Once students understand common affixes, teach them a framework for analyzing words step-by-step. A simple graphic organizer can guide them through:
1️⃣ Identify
🔎 Prefix
🔎 Root
🔎 Suffix
2️⃣ Define
🔎 Meaning of the prefix
🔎 Meaning of the root
🔎 Meaning of the suffix
3️⃣ Combine
🔎 Put the meanings together to infer the meaning of the word
4️⃣ Check
🔎 Use the inferred meaning in a sentence
🔎 Confirm if it makes sense in context
For example:
In the word disagree
✔️ Prefix: dis- (“not” or “opposite of”)
✔️ Root: agree
✔️ Combined meaning: to not agree
This aligns with morphological problem-solving frameworks supported by research from Goodwin & Ahn (2013), who found that explicit analysis and repeated practice improve comprehension and morphological awareness.
Model the process first. Then work through examples with students. Gradually reduce support until they can analyze words independently.
Step 4: Reinforce Affixes Across Units and Contexts
One of the most effective ways to make morphology stick is to use it everywhere, not just during vocabulary drills.
As you move through literacy-based therapy activities, encourage students to:
✔️ Look for target prefixes and suffixes
✔️ Add new examples to their vocabulary journal
✔️ Highlight affixed words in stories, articles, or science experiments
✔️ Use the definition card as a reference tool
SLP Now members can search the library for books and articles that contain specific prefixes or suffixes. This makes it easy to find contextualized opportunities for practice.
You can also bring in book-specific or article-specific organizers, allowing students to collect multiple examples of the same affix throughout the year.
Not a member yet? You can sign up for a free trial at slpnow.com/trial to access 400+ therapy plans!
Step 5: Build a Vocabulary Journal
A vocabulary journal helps students:
✔️ Track affixes
✔️ Write definitions
✔️ Record example words
✔️ See their progress over time
✔️ Add sentences and illustrations
This strategy supports deeper processing, described by Nagy, Berninger & Abbott (2006) as essential for moving new vocabulary from short-term exposure to long-term mastery.
Help students keep their affix cards, organizer examples, and unit-based words all in one place. I love creating student folders for this!
Putting It All Together
Morphology instruction doesn’t have to be complicated. By focusing on the most common affixes and embedding practice into everyday therapy, you can give students powerful tools for understanding and using new vocabulary.
These evidence-based strategies help students become confident, independent word learners, and help you make the most of your therapy time.
If you want ready-to-use materials for teaching prefixes, suffixes, and root words, you can download five activities for free and explore the full SLP Now membership. Sign up today at slpnow.com/trial!
References
Carlisle, J. F. (2010). Effects of instruction in morphological awareness on literacy achievement: An integrative review. Reading Research Quarterly, 45(4), 464–487.
Goodwin, A. P., & Ahn, S. (2013). A meta-analysis of morphological interventions: Effects on literacy achievement of children with literacy difficulties. Journal of Learning Disabilities, 46(6), 635–646.
Honig, B., Diamond, L., & Gutlohn, L. (2013). Teaching Reading Sourcebook. Arena Press.
Kieffer, M. J., & Lesaux, N. K. (2008). The role of derivational morphology in the reading comprehension of Spanish-speaking English language learners. Reading and Writing, 21, 783–804.
Nagy, W., Berninger, V., & Abbott, R. (2006). Contributions of morphology beyond phonology to literacy outcomes of upper elementary and middle-school students. Journal of Educational Psychology, 98(1), 134–147.
