How is the -ing form used in the following sentence?

To get in shape for that marathon, Shelby started running around the block a few times each morning.

participial phrase as an adjective
participial phrase as a noun
participle as an adjective
participle as a noun
gerund phrase as a subject
gerund phrase as a predicate noun
gerund phrase as direct object
none of these

Shelby started what? direct object

now what is "running" ?

The -ing form in the sentence "To get in shape for that marathon, Shelby started running around the block a few times each morning" is being used as a gerund phrase as the subject of the sentence.

A gerund is a verb form that functions as a noun, and it is created by adding -ing to the base form of the verb. In this case, the verb "run" becomes the gerund "running".

To determine how the -ing form is used in a sentence, you can look at how it functions within the sentence. In this case, "running around the block a few times each morning" is the main action taking place in the sentence, and it is serving as the subject of the sentence. Therefore, it is a gerund phrase acting as a subject.

Study about participles and gerunds here:

http://www.chompchomp.com/terms.htm

When you have figured this out, let us know.