Now, normally, I'm so against using a first language to teach a second. For our usual students, they have enough grammar instruction in their everyday schooling. All they have really is explanation, explanation, explanation but little, or more likely no, chance to practice. Students still can't form sentences after years of studying the language, so it's not explanation they lack but the opportunity to speak. Let 'em run around in the language. I'm not advocating no explanation—that'd be stupid. Just more time to practice.