Here's an idea for teaching younger CLIL students, for example, a TTO brugklas. When a teacher is providing spoken input, how can they check that their students are understanding what is being said? A CLIL traffic lights system might help.
Each learner has three cups - green, amber and red. At the beginning of the lesson they put their green cup on the outside, and the other two are stacked beneath it. Whilst the teacher is speaking, and as long as the learner is understanding everything, then they stay at green.
However, if the learner wants their teacher to slow down, or repeat something, then they can move to amber:
Finally, if the learner needs one-to-one assistance then they put their light at red (and if there are several red lights showing then these learners could be grouped together, which might help with differentiation) :