Although Valentina has lived in the United States for only 1 year, and her English skills are not especially strong, all of her classes at school are taught in English only. Which is this an example of:.

submersion.

Explanation:

Learning a second language apart from your normal native language requires work and dedication. And many approaches have been used in past(and still in existence) for students that wants to learn English language as a second language but the most common ones are the submersion and immersion.

SUBMERSION is a kind of learning model in which the student that wants to learn English language will be put with other students that are majorly Native English speakers.

And if you look back at the question, in Valentina's class all of her classes at school are taught in English ONLY. So, the learning model is that of SUBMERSION.