A level biology exam

In the exam we have coming up it says on our assignment brief that we need to:

explain how cells are organised into tissues, tissues into organs, organs into organ systems and organ systems into organisms.

We haven't covered this much in class and its confusing me, has anyone had this come up in an exam, if so what was the questions like?
Struggling to revise for it when its confusing me

Quite a common GCSE exam question.

1) Tissues are groups of cells with similar structures, working together to perform a shared function
2) Organs are Structures made up of a group of tissues, working together to perform specific functions
3) Organ systems are group of organs with related functions, working together to perform body functions