Change Idea Dosage: When Do You Have Enough of a Good Thing?

As we implement change ideas to help our students, measuring outcomes can help to determine if ideas are beneficial or not. The measures tell us if students got closer to our desired outcome. But once we identify a good idea, we need to understand more clearly how much of that beneficial practice students need. Time in classrooms is precious, and we need to ensure that students are getting what they need, but also that our time budget is well spent on all the things that matter. This brings us to the question of dosage.

Most of us know the basic principles of healthy living. We know we need to eat more healthy foods and get active on a regular basis. The proverb, “An apple a day keeps the doctor away” has been around since at least the 1800s. Much further back, Socrates wrote of the importance of physical training. But even once we know this, it prompts the question, “How much is enough?” Can one apple a day really keep us in good health?

Thanks to measurement in health research, we have some answers on this. Most people in modern work (with teachers often a notable exception) do a lot of sitting. Lots of sedentary behavior leads to several kinds of negative health outcomes, leading former Mayo Clinic director Dr. James Levine to declare that “sitting is the new smoking.” So at least some activity is necessary and good. But how much do we need during the day?

In 2021, Jonathan Smith and colleagues set out to test a theory of activity dosage. After testing baseline health markers, volunteers spent three weeks taking three-minute activity breaks every 30 minutes while a control group carried on as normal. They found that the intervention group improved—though not as much as they would have liked—on measures like fasting glucose. So the implication is that, not only is movement necessary, but that three minutes of activity per 30 mins is a minimum dosage to see improvements, and more might be needed to get patients where doctors want them to go.

There is similar work on diet. Someone, somewhere, be it a doctor or a parent, told us all to eat fruits and vegetables. But how much? Is it really just an apple a day to keep the doctor away?

In 2017, Aune and colleagues   published a meta-study, or a compilation study of 95 other studies, on diet. Their findings suggest that 800 grams of fruits and vegetables per day was the level, or dosage, at which all causes of mortality (e.g., cancer, coronary heart disease, stroke, etc.) seemed to be reduced. In practical terms, 800 grams is about six cups per day. (For reference, the photo below is 800 grams of fruits and vegetables, totaling about 290 calories, or 15% of the average 2,000 calorie daily diet). So fruits and vegetables are good for us, but this work gives us a sense of how much we really need to see a difference in our health.

These studies illustrate in health terms what we need to consider in classrooms. Measuring the initial impacts of change ideas can help us to determine which practices address students’ needs and which do not. But the next step is to determine the right dosage, so we know how much of a change idea is needed to support student growth. The activity to write about a text and give feedback using a rubric? That might need to be at least a weekly activity to have impact. Annotation? Students might need to practice that, at least a little, several days a week before you will see measurable impact.

A way to get at this dosage question is to collaborate with a couple of colleagues and mimic the Smith study on movement: Randomly assign (don’t volunteer) one of you to complete the change idea as you last measured it, assign one to complete it at some increased frequency, and assign one teacher to carry on as normal. Follow this for a couple of weeks. Measure all the groups before and after, discuss the results, and see what you find.

You might find a little walk every half hour does some good. Or you might find that an apple a day is about five apples short of your goal.


  1. Smith, JAB, et al. (2021). Three weeks of interrupting sitting lowers fasting glucose and glycemic variability, but not glucose tolerance, in free-living women and men with obesity. Am Jnl of Physiology Endocrinology and Metabolism, 321, E203-E216.  
  2. Aune, D., Giovannucci, E., Boffetta, P., Fadness, L.T., Keum, N., Norat, T., … Tonstad, S. (2017). Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. International Journal of Epidemiology, 46(3), 1029-1056. doi: 10.1093/ije/dyw319
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