They're present participles as they're replacing a relative clause. The classroom is clean and bright, which makes it a nice place to study. -relative clause The classroom is clean and bright, making it a nice place to study. - participle clause A small rug lies in front of the bed, which adds a cozy touch to the room. A small rug lies in front of the bed, adding a cozy touch to the room. As Dan says, in order to be a gerund it would have to function as a noun. In such cases, the gerunds are usually activities. Travelling to work is my least favourite part of the day. - gerund as you could replace travelling with journey, trip, etc. The journey to work ... Travelling to work, I realised I'd left the iron on. - participle as it is a reduced clause: as/while I was travelling ... While I was travelling to ...

not gerund definitely

They're definitely not gerunds (i.e. not functioning as a noun). So, must be the other. Hopefully a more professional 'grammarian' will render an opinion.

In #2, "adding a cozy touch to the room" is an adjective phrase that modifies "rug". This becomes especially clear if you move that phrase to where it works best - the beginning of the sentence: "Adding a cozy touch to the room, a small rug lies in front of the bed." It is best to place phrases next to the words they modify. #1 is a poor sentence because the phrase "making it a nice place to study" does not clearly modify any word. (What makes it a nice place to study?) Rather, it is a whole new thought. You need a relative clause as in Tim's example or a compound sentence: "The classroom is clean and bright and that makes it a nice place to study." When you say it that way, it is clear what makes it a nice place. Another way to say it clearly would be "The classroom being clean and bright makes it a nice place to study." A more subtle issue with #1 is that it relies on "making" to be its principal verb. "Making" is the word that expresses the principal action of the sentence: something MAKES it a nice place. But "making" is not a verb. Participles can never be verbs.

In the sentences you provided, "making" and "adding" are present participles, not gerunds. Here’s the distinction: 1. Present Participle: A present participle is a verb form that ends in -ing and is used to create verb tenses or to act as an adjective. In these sentences, the present participles are used to add additional information or describe an action related to the subject. 2. Gerund: A gerund is a verb form that also ends in -ing but functions as a noun. Examples with your sentences: 1. The classroom is clean and bright, making it a nice place to study. * "Making" is a present participle describing the result of the classroom being clean and bright. 2. A small rug lies in front of the bed, adding a cozy touch to the room. * "Adding" is a present participle describing what the small rug does to the room. In these sentences, "making" and "adding" act as present participles providing additional descriptive information.