Run-on sentences are a grammatical problem that affects second graders because they have only begun to learn about compound sentences in first grade. According to the Common Core State Standards, second graders should be able to write both simple and compound sentences. Notwithstanding, activities on how to correct run-ons are a foundational tool for those just learning how to use written language to express complex thoughts.
Separate Long and Short Run-ons
This activity will teach second graders that a run-on sentence doesn't have to be long; it simply needs to contain at least two independent clauses that aren't joined by a conjunction. For this activity, you will provide a list of run-on sentences. The students' job will be to correctly insert a period and capital letter to separate each run-on into stand-alone sentences. Every sentence you provide will be a run-on, though some should be very short.
For example, if you offer the run-on "Jack has a car it is red," students should correct it like this: "Jack has a car. It is red." You can alternate short run-ons with long ones, but limit long run-ons to only two independents clauses unless students demonstrate that they are ready for longer ones.
Snip the Sentences
Another fun way to teach second graders how to separate run-on sentences into independent clauses is to have students physically separate the clauses. Write run-on sentences of different lengths onto individual slips of paper that are about 11 inches long. Have your students gather in front of you. Select one student to be your snipper, and hand him or her a pair of safety scissors. Display a run-on sentence and ask the class -- as a group -- to decide where the sentence should be snipped. Once they answer correctly, have the snipper snip the sentences apart. You can then hand the individual clauses to other students, who can write in periods and capital letters to make the clauses complete sentences.
Add Commas and Coordinating Conjunctions
Because second graders should be able to produce compound sentences, it is important to teach them that run-ons can be corrected with commas and coordinating conjunctions. Provide students with a list of short run-on sentences. Instead of having them insert periods and capital letters, have them place a comma after the first independent clause, followed by an appropriate coordinating conjunction.
For example, if the run-on is "Harry built a house it was ugly," students could write "Harry built a house, and it was ugly." Show them that the sentence could also be written as: "Harry built a house, but it was ugly," and discuss with students how the coordinating conjunction can change the attitude of the statement. Limit conjunctions in this lesson to "and" and "but," as these are the most basic.
Identify Simple, Compound or Run-on Sentences
This activity will serve mostly as a review, but will also introduce the lesson that a coordinating conjunction doesn't always require a comma when used to join two independent clauses. Write a sentence on the chalkboard and ask the class to identify it as either a simple sentence, a compound sentence or a run-on. As they identify sentences correctly, write sentences that are longer and more difficult. Occasionally write a compound sentence that takes a coordinating conjunction, but no comma. Explain that a very short compound sentence doesn't require a comma if the sentence will still be clear without it. For example: "Jack ran and Jill followed" is permissible.