fossilisation occurs when the errors are not corrected in the first place
Fossilization occurs when the learner stops learning – when they are no longer exposed to correct forms and/or stop trying to improve.
If they have several years of formal language education left, the chance not correcting their mistakes now is going to lead to fossilization is minute.
If they have a significant amount of correct input and a focus on output – putting their own thoughts into English – they will avoid fossilization.
Spending much class time on error correction drastically reduces the amount of input and output they process. It drastically slows down their progress. If you have a healthy amount of input and output, they will make fewer and fewer mistakes without needing to spend class time focusing on correcting mistakes.
Loudine,
Pair and small group work works well in mixed level classes if you can avoid the higher level students doing all the work. One way to try it is to assign individual roles – like group leader, note-taker, illustrator, editor
If you make the highest level student the group leader and make sure they don’t do the writing or other work, it can help make the project more useful.
Also, don’t expect good results the first or first couple of times you do it. Students have to get used to something new before they invest in it.
Another way to use pair and group work in mixed level classes is to put similar levels together and give them an activity that fits their need or vary your expectations for how much or what kind of output you expect from the lower and upper levels.