Naturally, it’s less than ideal to offer a Spanish course without offering the students that chance for authentic conversation practice with one or more Spanish speakers. From my experience in learning several languages, the true joy of learning a language is being able to communicate using the vocabulary you’ve learned, however limited that may be.
I’m currently teaching Spanish for the third school year. The first time I taught Spanish in a traditional high school classroom, I jumped in part way through the school year at the request of a non-Spanish speaking teacher who was using Abeka DVDs to teach Spanish. The students were bored and doing poorly. For them, that approach was entirely too passive. In the last few weeks of the school year, I tried to heighten their interest in Spanish by making our class time much more communicate and interactive. It worked–for some of them.
This year, since my schedule as a mother of preschoolers only allowed me to offer one hour per week of class time, we are trying a blended approach, where the students practice using the web app Duolingo at least 5 days a week for a total of 60 minutes of practice per week. I’ve allowed them to work ahead on Duolingo much as they like. For the most part, they have thrived on it. In our class times, I pull from Abeka Spanish, again trying to keep class as interactive as possible, but also providing the grammar explanations that Duolingo lacks.
In summary, if at all possible, find a Spanish speaker who could be at the very least a coach and resource person for your class. Perhaps there are Latinos in your community whom your class could visit and even sing for. (CLP offers a song booklet with choruses, some of them translated from familiar English choruses, called Despertad y Cantad. They also have audio CDs of the entire booklet.) If you can’t find any Spanish speakers who are available, I think Duolingo on its own would be a decent option. Admittedly, your students will learn to read and write Spanish much more quickly than they will learn to speak and understand what they hear, but at least they will have made a start.