Teaching 1 hour a week for only 10 weeks must be a difficult task. I'm sure parents are expecting results and spending 4 classes on the same topic would be detrimental. One way to see results is to teach your lesson, send interesting practice activities for home (try finding free online games and activities and creating board games they can play with their families), and then reviewing for a couple of minutes in the next class. Also, try getting a song related to each topic so they can be singing at home. If you have a web page, you can upload or post it there. You can do some much for FREE with the internet and get great results. Of course, parental involvement is a must. Good luck!
