Sentence combining as a writing intervention

By the IEP Atlas editorial teamLast updated November 1, 2026

Short answer

Sentence combining is a writing intervention in which students join two or more short sentences into one longer, clearer sentence, using connectors such as and, but, because, who or which. Teach one combining type at a time, model it, practice orally and in writing, then have students apply it in their own drafts. Measure transfer in real writing, not only on worksheets.

A student who writes "I have a dog. My dog is brown. He is big. He likes to run." knows what to say but not how to package it. Sentence combining gives that student a set of tools for joining ideas: "My big brown dog likes to run." The content stays the same; the sentence does more work.

The What Works Clearinghouse guide on teaching elementary students to write recommends teaching students to construct sentences for fluency, meaning and style, and sentence combining is one of the main ways teachers do it.^[1] It suits students whose writing is choppy, repetitive or full of run-ons, and it works across grades because the sentences can be as simple or as academic as the student needs.

This page covers the combining types, a 10-week schedule, one student's data and how to measure progress. For the broader set of writing goals, see the IEP goals for writing pillar.

The combining types, in teaching order

Teach from simplest to hardest. Most students need several weeks on each of the first four.

Type	Two short sentences	Combined	Signal words
Compound subject or verb	Sam ran. Sam jumped.	Sam ran and jumped.	and, or
Adjective insertion	The dog barked. The dog was small.	The small dog barked.	(none)
Compound sentence	It rained. We stayed inside.	It rained, so we stayed inside.	and, but, so, or
Prepositional phrase	We ate lunch. We were in the park.	We ate lunch in the park.	in, on, after, during
Complex sentence (cause, time)	We stayed inside. It was raining.	We stayed inside because it was raining.	because, when, after, although, if
Relative clause	My aunt lives in Ohio. She is a nurse.	My aunt, who is a nurse, lives in Ohio.	who, which, that
Appositive	Mr. Lee coaches soccer. He is my neighbor.	Mr. Lee, my neighbor, coaches soccer.	(commas)
Participial phrase	Maria opened the box. She smiled.	Smiling, Maria opened the box.	-ing, -ed openers

The compound sentence goals page has goals for the middle rows, and IEP goals for writing simple sentences covers students who are not yet ready to combine.

What a sentence combining lesson looks like

A 15- to 20-minute lesson, three or four times a week, is enough for most students.

Review (2 minutes). Combine two sentences with a type already taught.
Model (4 minutes). Show the new type with a think-aloud: "Both sentences are about the dog. I can tuck 'small' in front of 'dog.'"
Oral practice (4 minutes). Students combine pairs out loud. Saying it first is easier than writing it.
Written practice (5 minutes). Students combine 4 to 6 sets. Accept more than one correct answer, and talk about which reads best.
Apply (3 to 5 minutes). Students find two choppy sentences in their own draft and combine them.

The apply step is the one teams skip, and it is the one that makes the skill transfer. A student who combines perfectly on worksheets and writes choppy paragraphs has not learned to use the tool.

Scenario: Jordan's 10 weeks

Jordan is a fictional fifth grader with an IEP in written expression. All numbers are illustrations.

Baseline, January 6 to 10. Three 10-minute writing samples on picture prompts. Jordan writes 9, 11 and 10 sentences. Every sentence is simple; 6 of 30 are run-ons joined with "and then." Average sentence length is 6.5 words. Correct word sequences in 3 minutes: 21, 24, 22.

Plan. Sentence combining, 20 minutes, 4 days a week, with his special education teacher. Weeks 1 to 2: compound subjects and verbs, adjective insertion. Weeks 3 to 5: compound sentences with and, but, so. Weeks 6 to 8: complex sentences with because, when, after, if. Weeks 9 to 10: relative clauses with who and which.

Progress probe. Every 2 weeks, a 10-minute writing sample on a new prompt, scored for the share of sentences that are correctly combined (compound or complex), plus correct word sequences on a 3-minute probe.

Week	Date	Correct combined sentences	Run-ons	Avg sentence length	CWS (3 min)
Baseline	Jan 10	0 of 10	2	6.5 words	22
2	Jan 24	1 of 9	2	7.0	24
4	Feb 7	3 of 10	1	8.1	27
6	Feb 21	4 of 9	1	8.8	29
8	Mar 7	5 of 10	0	9.4	31
10	Mar 21	6 of 10	0	10.2	34

By week 10, 6 of 10 sentences in Jordan's own writing are correctly combined, run-ons are gone and correct word sequences have risen. His teacher notes that he overuses "because"; the next unit adds variety with although and relative clauses.

His IEP goal, from the sentence combining goal template: "In a 10-minute writing sample on a grade-level prompt, Jordan will correctly use compound or complex sentences in at least 5 of 10 sentences, on 3 consecutive biweekly samples."

How to measure sentence combining

Measure two things: whether the student can combine when asked, and whether combining shows up in their own writing.

Combining probe. Give 10 sets of 2 or 3 short sentences. Score each as correct if the combined sentence is grammatical, keeps the meaning and uses the target type. This shows the skill.
Writing sample. Give a timed prompt and count the share of sentences that are correctly combined. This shows transfer.
Correct word sequences. A 3-minute probe scored for correct word sequences is a general measure of writing quality that rises as sentences improve. It has been studied as a valid indicator of written expression since the early 1980s.^[2] The TWW and CWS guide explains scoring.

Record scores on the rubric scoring data sheet or a simple tally, every 2 weeks.

Rules and options, and where they differ

Question	Who decides	Varies by state or district?
Whether sentence combining is taught in core writing	District curriculum	Yes
Which grade-level sentence standards apply	State English language arts standards	Yes
Whether a student gets it as specially designed instruction	IEP team, from present levels	No; individual decision
How progress is measured and reported	IEP team; the IEP must state the method and schedule^[3]	No
Whether writing accommodations, such as speech-to-text, are allowed on state tests	State testing policy	Yes
Whether state writing tests score sentence variety	State test rubric	Yes

Common problems

Worksheets without transfer. Always end with combining in the student's own draft.
Teaching too many types at once. Stay on one type until the student uses it in writing.
Treating longer as better. A 40-word sentence is not the goal. Clarity is. Have students read both versions aloud and pick the clearer one.
Ignoring punctuation. Compound sentences need commas before the conjunction; appositives need commas on both sides. Teach punctuation with each type.
Skipping oral practice. Students with language needs benefit from saying combinations aloud before writing them. SLPs can reinforce the same types in therapy.

Goals and next steps

The sentence construction goals library has templates for each type, including combining with who, which, that or an appositive and complex sentences with a given conjunction. The written expression goals library covers longer writing. When students are ready to build paragraphs from combined sentences, see the paragraph writing IEP goal page, and for planning whole pieces, see self-regulated strategy development for writing. Written expression is defined in the glossary.

Frequently asked questions

What grade level is sentence combining for?

Any grade. Younger students combine short sentences with and or adjectives; older students combine with relative clauses, appositives and participial phrases. Match the sentence types and the vocabulary to the student's writing and grade-level standards.

How long does a sentence combining intervention take?

Most students need several weeks per combining type, in 15- to 20-minute lessons three or four times a week. A program covering four to five types typically runs 8 to 12 weeks before a full review.

How do I know sentence combining is working?

Check the student's own writing, not just practice sets. Count the share of correctly combined sentences in a timed writing sample every 2 weeks, and watch run-ons drop and correct word sequences rise.

Use it in IEP Atlas

Sources

Teaching Elementary School Students to Be Effective Writers, What Works Clearinghouse, Institute of Education Sciences
Correct Word Sequences: A Valid Indicator of Proficiency in Written Expression (Videen, Deno, and Marston, 1982), Institute for Research on Learning Disabilities, University of Minnesota, via ERIC
34 CFR §300.320: Definition of individualized education program, Legal Information Institute, Cornell Law School

Written and checked by the IEP Atlas editorial team under our editorial policy. This guide describes general practice and federal rules. It is not legal advice; your state may add requirements, and the IEP team makes the decisions for each student.