Teaching in 72,000 Seconds

A typical lesson, in a typical classroom has 72,000 seconds with which to engage students. The math is not too complicated: a 40 minute period, with 60 seconds in each minute, and 30 students. 40 x 60 x 30 = 72,000. This math reflects the fact that every student is experiencing every second simultaneously. Each second is actually 30 seconds.

The question is how many of those 72,000 seconds are being planned for and actually used. Too many times teachers assume that they they are making full use of these 72,000 seconds when in fact they are making use of less than 3% of them.

One of the most common forms of instruction that I witness involves something that I call a guided lecture. This something like a lecture, but the teacher doesn’t want to just flat out dominate with their own voice, so they ask a question every 45 or 60 seconds and when a student answers it gives the teacher permission to continue talking. In most teachers’ minds, they believe they are engaging all of their students in a class discussion. In reality, they are engaging one student at a time for a few seconds. Students taking turns being engaged would generate about 1,800–2,000 seconds of engagement, or less than 3% of the 72,000.

A common misconception around this kind of analysis is that teachers should then plan for 72,000 seconds of engagement. this is a bit unrealistic, and if it were achievable, it would probably be as ineffective as planning for only 2,000. Instead, I suggest teachers should offer a balance in most of their lessons, aiming for 20,000–25,000 seconds of planned engagement.

20,000 seconds of engagement affords the teacher plenty of time to provide direct and or explicit instruction that might be needed as well as ample opportunities for students to process and apply some of that knowledge to help it go into long term memory. This is not a very radical change to teaching, but it is a simple and powerful tool to help people teach in a way that more closely matches how they think they are teaching.

the next time you are planning a lesson, or talking with a colleague about their plans, consider using this tool to calculate how much engagement time is planned and whether or not it matches your intent.

Public Educator: teacher, teacher trainer, assistant principal, principal, special ed. director, assistant superintendent, and 14 years as a superintendent.