I think the point of highlighting the fact that this is an ESL class, meaning it is geared towards helping Spanish speaking kids learn English, is to imply that

I think the point of highlighting the fact that this is an ESL class, meaning it is geared towards helping Spanish speaking kids learn English, is to imply that most instruction is in English but the instructors fall back on Spanish when necessary. Only one class per day was taught exclusively in Spanish. So his or her kids are getting exposure and limited instruction in Spanish, but it isn't full immersion. At least, that's how ESL worked when I was in school - I invite the above commenter to correct this is it is not correct.