The Key Input: Session Execution


Session execution or Session Execution Rate (SER) is the key input metric we track at Once. This metric tracks whether or not instructional sessions are occurring as scheduled. If sessions are not occurring Once will not be effective, no matter how well trained and coached the instructor is. Therefore to improve school performance, the first thing we attempt to optimize is session execution.


Session Execution is the number of sessions that have occurred divided by the number of sessions scheduled. This shows how many days of instruction happened out of the total possible days.

The numerator of Session Execution, number of sessions that have occurred, is the number of dates in the instructor log where an ending cycle number has been entered after instruction has taken place (showing that a student progressed forward in Once that day).

The denominator of Session Execution, the number of scheduled sessions, is the number of dates in the instructor log prior to today that are either:

  • Blank (we don't know what happened on that day)

  • Have a cycle entered (the student had a session and progressed in Once that day)

  • Have an "s" indicating a student absence

  • Have an "i" indicating an instructor absence

  • Have an "o" indicating that the instructor was unable to provide instruction because of another responsibility.

An "X" in the log indicates that there was no school or no session scheduled for that day. Typically an "X" would indicate a scheduled school holiday or vacation. An "X" does not "count against" Session Execution (it is not in the denominator) because it would not have been possible to provide a session that day.


On Monday a student progressed from Cycle 15.1 to 16.1. On Tuesday the student progressed to Cycle 17.1. On Wednesday the student was absent. On Thursday the instructor had other responsibilities. Friday was a snow day so there was no school.

In this example Session Execution for the week would be 50%. Two sessions occurred out of four that could possibly have occurred. Friday is not factored into the count of possible sessions because there was no school that day.

Session Execution Excluding Student and Instructor Absences

When schools are trying to improve the rate of Session Execution, the first place to focus is days when students were in school but didn't get Once even though they were supposed to. In the School and Instructor tables, we show SER (Session Execution Rate) with no student absences both for the year and the preceding 30 days. This calculation shows what fraction of sessions scheduled to occur actually occurred on days when students were in school.

In those tables we also show SER (Session Execution Rate) with no student or instructor absences both for the year and the preceding 30 days. That goal is that that number is 100%, which means that Once is always delivered on days when the student and instructor are both present in school. The typical reason why this would not be 100% would be if the instructor is pulled from instruction during the day to cover other responsibilities within the school.

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