I found that using movies or TV shows was a great way to gauge their interest.
Choosing movies or shows that are simple, slower, and don't use extremes in language work really well.
First you would watch the movie/show and find a section between 5 to 10 minutes long that meets the above criteria. Get that section into your classroom anyway that best works for you. Then you need to type up the script and remove words; easy to hear words for low levels and up to whole phrases for high level.
Then play the movie WITHOUT showing it to them, only the sound. The must listen and fill in the blanks. Next, play the movie and again, no picture. Then correct and make sure they all have the correct answers. Finally, you show the video to them to allow them to see what they heard. You can make it more or less difficult and also split up scenes. It works to catch attention and interest. They will want to see what is happening. Be careful to not use it too much, or they might get complacent and wait for the video.
After the video is shown, put them into groups and have them make an ending to the movie/show. Have the groups each act out their ending and hopefully, they will start to use more English.