The goal of science is to explain the natural world.  As such, explanation should be our goal in science education as well. In this section, we provide resources for helping students build explanations of anchoring phenomena during an MBI unit.

Here is an example evidence-based explanation from the example Axial Seamount unit designed for an 8th grade Earth Science class. The driving question the students were answering was: How did Axial Seamount come to be where it is today? The explanation layers three important aspects: 1) the story of what happened, 2) important science ideas necessary to explain mechanistically what happened (e.g., subduction, convection currents, etc.), 3) and evidence of how we know each aspect of the explanation.

Important to a scientific explanation is that it is causal.  In other words, explanations should answer why the anchoring event happened. The why is often invisible. Below is a great resource from the Ambitious Science Teaching group on moving students from simple "what" explanations to "why" or fully causal explanations. In the example above, the "why" of the explanation is the movement of energy from the interior of the earth through convection currents.

In our MBI template, you are asked to write two different example explanations. The first, the 'Target Written Explanation', is a fully causal accounting of the story. To be a fully scientific explanation, the important science ideas (e.g., natural selection, convection currents, radioactive decay, etc.) should be integrated into the explanation. This target written explanation will help you identify the important science ideas to structure your unit around.


In Stage 5 of the template, you are asked to write an example 'Final Evidence-Based Explanation'. This is similar to the target written explanation, but it also include statements connecting the claims to specific pieces of evidence. It is a full causal story of the phenomenon, integrates the important science ideas at play during the unit, and provides the evidence for how we came to understand the explanation. This is merely an example of what students could produce. The students will find multiple ways to write their own explanations!

What counts as evidence?

For a final, evidence-based explanation at the very end of the MBI unit, we want students to not only provide a causal account of the anchoring phenomenon, but to support their explanation with evidence. In science, evidence is most often quantitative or qualitative in nature. This is the same for the science classroom.  For example, student investigations of the soda can crushing lab will lead to quantifiable data about the relationship between temperature and pressure to use as evidence in the explanation of the tanker implosion phenomenon. However, especially at younger grades, we can use specific activities as evidence. For example, in building our explanation of the impact of the reintroduction of wolves into Yellowstone, the Oh Deer activity helps us understand the concept of carrying capacity and limiting factors. See our Evidence-Based Explanation Rubric below for ways we think about assessing students' final evidence-based explanations at the end of the unit.