Make students talk

My school is an American international school for Vietnamese kids. Most of our students can speak real good English, because all the subjects are taught in English.
My kids take Mandarin everyday for 50 minutes,there is not much time for each single student to practice in the class when you try to fit teaching, practicing and assessments into one short period.

How to get these kids open their mouth to actually speak and practice Chinese? I gave them assignments of reading the texts at home, I knew they wouldn't do it though. Last month I started to learn about using Voicethread. I used it when I taught comparative sentences, I put 10 slides of contrast pictures, and asked my kids to leave their voice comments for each picture. It's hard to make them to get used to the new tool. But it really forced them to speak and gave me a better insight of what they have learned.

I did another project called "you are the fashion editor" after I taught them vocabulary about clothes. They have to describe and compare what the stars wearing on the pictures. Their work looked pretty impressive. I played it in the class, asked them to do peer study, listen to each others' comments and find out the good parts and parts need to be improved.

I'm not saying I have found the way, but Voice thread is a good tool to let students practice their speaking.