If your child is a beginner learner, then you have found the simplest method to help them start speaking English fluently!
Encourage your child to actively engage with every lesson. Doing the hand gestures will help them to memorize all the new vocabulary; speaking and singing will improve their pronunciation and fluency.
You can also use the PDF translations (in the drop-down menus of each video lesson) to explain to your child what is happening in the presentation scenes (Scenes 1, 3 and 7). This will help your child to understand the lesson.
Learning occurs when a child makes the effort to interact with the lesson. Therefore you should give praise when your child makes an effort to speak, do the gestures or sing along with Sam and Mel. The child's reward is their sense of accomplishment at succeeding to speak. Children can also earn medals by clicking on the green button (top right of each video) each time they watch a lesson or exercise.
If the child thinks they are ready for the next lesson, it is a good idea that they do the lesson in the parent's presence to show that they can achieve the following goals:
The child's performance does not have to be perfect before moving on to the next lesson. They can always come back to review and practice a lesson again in the future.