Prettejohn,
Do you speak any Spanish? If so, I would hammer them with it at home as well. Right now I think they are waiting out the Span part of the day until the easier (for them) English part starts. The best thing might be a Span only school. However, if that is drastic, they will certainly pick up some of the Span in your current situation. We have a 14 month old and my wife speaks to her in her native language and I do mostly (not fluent) Span, and the nanny only speaks Span. I am hoping she is fluent in Span when we leave.
Do you speak any Spanish? If so, I would hammer them with it at home as well. Right now I think they are waiting out the Span part of the day until the easier (for them) English part starts. The best thing might be a Span only school. However, if that is drastic, they will certainly pick up some of the Span in your current situation. We have a 14 month old and my wife speaks to her in her native language and I do mostly (not fluent) Span, and the nanny only speaks Span. I am hoping she is fluent in Span when we leave.