Teaching and learning
Same lesson. Different starting points.
What students already know shapes how they make sense of what you teach next.
Imagine two people learning a new recipe from the same cooking video. They have the recipe in front of them and want to make the same dish.
At step two, the chef says, “Blanch the vegetables.” Then the video moves on to making the sauce.
One person has blanched vegetables before. The instruction connects with something they already understand. They know what it involves, so the next part of the explanation makes sense.
The other has never learned the technique. They pause. There is a missing piece in the explanation before they can make sense of what comes next.
For this recipe, blanching means briefly cooking the vegetables in boiling water, then cooling them quickly in cold water to stop the cooking. That is one common method; the details depend on the vegetables and recipe.
But a short definition is not the same as knowing how to perform the technique. The second person may need to see it demonstrated before continuing.
One person is learning a recipe. The other first needs to learn a technique the recipe assumes they know.
Teachers can encounter a similar difference when introducing a new idea. An explanation that feels clear to us may depend on earlier understanding a student has not yet built.
The two learners heard the same words, but could not make the same connections. Another viewing can help when something was missed. If the technique was never explained or demonstrated, repeating its name still leaves the learner needing that foundation.
This is prior knowledge: the facts, ideas and skills a learner brings to a new explanation. It gives new information something to connect with. In the cooking example, that includes knowing how to blanch vegetables. In a lesson, it may also be an earlier concept or a relationship between ideas.
In How People Learn, the National Research Council explains that existing knowledge and skills influence how learners interpret new information. Teachers therefore need to attend to the understanding students arrive with. The principle applies to younger learners and students in higher education.
Carnegie Mellon's Eberly Center describes how relevant, accurate prior knowledge can support learning, while insufficient, inaccurate or unused knowledge can get in the way. The cooking scene illustrates one possible missing foundation; prior knowledge can also include ideas that need correcting.
The relevant foundation changes across ages and subjects. A younger reader may need help connecting letters with sounds. A school science student may need to understand what a measuring tool shows. A university student reading history may need background about the period to follow an argument. These are different kinds of starting knowledge, rather than one fixed sequence every learner must follow.
For a teacher, one useful question is: “What does this explanation assume the student already understands?”
If an explanation is not making sense, you might ask the student how they understand one key part. Listening can help you notice an earlier idea that needs revisiting or an unfamiliar technique that needs demonstrating. Then return to the new explanation and help the student connect it with what they have just learned.
Prior knowledge is one influence on learning. Attention and the clarity of the explanation matter too, so a pause alone does not establish a missing foundation. Listen to how the student understands the information before deciding what to revisit.
Both learners are hearing the same recipe, but making sense of it from different starting points. In the classroom, noticing those starting points helps us choose the next explanation.
Before we move on, it helps to connect the next idea with what the student already understands. A connection that feels obvious to the teacher may need to be built with the student first.