This paper describes Toccata, an activity-centric system for classroom orchestration. Through preliminary fieldwork, we identified three main challenges in the management of digital activities in classrooms: 1. Poor infrastructures lead to breakdowns in the activity 2. Activity structures are idio-syncratic (they vary widely and are rarely shared); and 3. Orchestration is difficult because teachers lack an overview of the unfolding activities. We developed Toccata to support activity scripting and orchestration in situations with unreliable connectivity. Based on a preliminary trial, we outline directions for activity-centric orchestration systems: 1. Focus on timing; 2. Provide several levels of awareness; 3. Support activity suspend and resume in changing contexts.