ONE OF THE MOST CHALLENGING PARTS OF TEACHING 90% IN THE TARGET LANGUAGE is keeping your students in the target language, too. What are some strategies we can implement to encourage and support our students? Here is an idea that works really well in my classroom for my elementary Spanish students, and is applicable for all levels:
INCORPORATE ACTIVITIES THAT STUDENTS don't want to "lose"...in other words, activities that act like privileges that continue in the classroom as long as the target language is spoken. For example, this spring my 4th graders followed an Iberian Lynx breeding center in Spain via a live cam on the net (link here!). As long as their reactions and comments were in Spanish, the live cam stayed on the whiteboard. If English became the mode of talking about the lynxes, the cam went off. Since it was of such high interest for my students, they stayed in Spanish the vast majority of the time because they didn't want the cam turned off.
THE SAME DYNAMIC can be created with other live cams, videos, games, and more that are high interest and motivating. If speaking in English means the game is now over, for example, most students will strive to use what they know rather than have the game end. As the teacher, in order to support this output, you have to be sure to choose activities that are accessible to students in terms of what they know and can do in the language; if they don't have enough vocabulary to interact, it's not going to work for them, and they will revert to English.