Refers to a ‘block’ of time – for example, a number of weeks – being devoted to a particular topic or prescribed set of learning objectives/outcomes. It can also indicate a way of organizing the school day using long class periods (more than 60 minutes and typically 90-minutes long) to incorporate more activities and materials to engage the learners. It can be used to make time allocation more flexible to enhance activities such as project- and problem-based learning.