If this question refers to a child under 2.5, these children will most often join a group having some kind of a language lesson. They are absorbing everything, but you may get few responses from them.  If the question is referring to a 2.5 – 6-year-old child, if a child is interested in what is being shown in the lesson they will attend to what is being shown.  If they are not interested in the lesson content, what is the point of trying to engage the child?  

It is possible to do grace and courtesy lessons to the group about how to sit for a lesson, how to ask to attend a lesson, and how to ask if they can leave a lesson so that no child is forced to join a lesson of no interest to them.

In a 2.5 – 6 environment, there are very few whole group lessons and those that are done are typically grace and courtesy lessons, perhaps some singing together, perhaps sharing some news.  It is difficult to plan a lesson that is equally of interest to a 2.5-year-old and a 6-year-old. So, the lessons created for the whole group have some importance to the day-to-day living experiences of the group. Content lessons are generally individual at the 2.5 – 6 level except for the instances mentioned above.