Phonics, Spelling, & Grammar Resources

Teaching the double consonant “mm” can be challenging for students as they learn when and why letters are doubled in English spelling.

The double consonant “mm” is not a standalone rule. It is part of broader spelling patterns, including the 1–1–1 doubling rule and patterns within multisyllabic words.

Understanding how the double consonant “mm” works helps students maintain correct vowel sounds, improve spelling accuracy, and build confidence in reading and writing.

What is a Double Consonant?

A double consonant occurs when the same consonant appears twice in a row within a word (e.g. mm, tt, ss).

Double consonants appear as part of common spelling patterns in English and are often found in words with short vowel sounds.

Examples:

• humming
• summer
• comma

When to Use the Double Consonant “mm”

1. Doubling “m” When Adding Suffixes (1–1–1 Rule)

The most reliable time students will use the double consonant “mm” is when adding suffixes.

If a word has:

• 1 syllable
• 1 short vowel
• ends in a single consonant

→ double the final consonant before adding a suffix.

Examples:

• hum → humming
• drum → drumming
• skim → skimming

2. Double “mm” in Multisyllabic Words

The double consonant “mm” also appears in many multisyllabic words

Examples:

• summer
• comma

👉 These are best taught as recognised spelling patterns, not strict rules.

Important Clarification

Most short words ending in m use a single m.

Examples:

• jam ✔
• him ✔
• drum ✔

👉 Doubling typically occurs when adding a suffix or in known word patterns.

Common Student Difficulties

Forgetting to Double When Adding Suffixes

Students may write:

• huming instead of humming
• druming instead of drumming

Overgeneralising Doubling

Students may incorrectly write:

• jamm instead of jam

This happens when students apply doubling rules without checking vowel patterns.

Difficulty with Multisyllabic Words

Words like summer and comma are often memorised patterns rather than rule-based

Words That Do NOT Follow a Simple Doubling Pattern

Many words contain m but do not involve doubling. These should be taught as standard spelling patterns.

• program
• diagram
• random
• system
• autumn
• column

Teaching Tips for Double Consonant “mm”

• Focus on the 1–1–1 rule for suffixes
• Use word building activities (hum → humming)
• Teach summer and comma as pattern words
• Avoid over-teaching “mm” as a strict rule
• Reinforce through reading and spelling practice

Why the Double Consonant “mm” Matters

Understanding the double consonant “mm” helps students:

• apply suffix rules correctly
• improve spelling accuracy

Strong knowledge of spelling patterns supports both reading fluency and written communication.

Final Thoughts on Teaching the Double Consonant “mm”

Understanding the double consonant “mm” helps students apply spelling patterns more accurately, particularly when adding suffixes such as -ing and -ed. Rather than teaching “mm” as a standalone rule, it is more effective to focus on the 1–1–1 doubling pattern and recognise common word forms like summer and comma.

With clear modelling, repeated exposure, and targeted practice, students can develop confidence in recognising when doubling is required and when it is not.

Want to make teaching double consonants easier? Explore our ready-to-use resources below to support your phonics lessons and reinforce student learning.