## How to Activate Prior Knowledge

[ Music ]>>What are some other teaching
practices that leverage what we know about the role prior knowledge
plays in learning? Earlier I described a method
I use in my statistics course, a method known as peer instruction. This method does a great job of helping
students activate prior knowledge. Here’s how it works. I ask my students a multiple choice question. In statistics mine are often concept questions,
but other kinds of questions can work well, too. Students take a minute or two
to think about and respond to the question using a classroom
response system of some kind. I take a look at the results and based
on those results do one of three things. If most of the students, say 85% or 90%,
have answered the question correctly I know that we don’t have to spend too
much more time on the question. For most students their prior knowledge
was sufficient to answer correctly. We’ll discuss the question briefly since some of the students might have been
guessing, but move on fairly soon. If most of the students, again say 85% or 90%, answer incorrectly then I know their
prior knowledge isn’t up to the task. We need to backtrack. I might explain something again or show them
why the most common wrong answer is, indeed, wrong or have them tackle an
easier question as a first step. Ideally when I ask a question like
this the students are split among two or three answer choices. This indicates to me that the
question is the right difficulty level, not too hard, not too easy. There’s some useful prior knowledge in the room, so I have my students pair
out and discuss the question. I ask them to explain their reasoning to each
other, and I’ll often say things like if you and your partner already
agree on the answer talk about it anyway because you might both be wrong. After a second round of voting we then
discuss the question as a whole class. I’ll ask students to argue for
and against various answer choices and try to guide the class to the correct answer and the correct reasoning using the
students’ own comments and perspectives. By the time we get to the class wide discussion
phase the students have had two important opportunities to activate their prior knowledge. First, when they thought about the
question individually and, second, when they discussed the question in pairs. Typically this means that a
lot of students have something to say during the class wide discussion and
they’re more prepared to follow and understand that discussion, as well, because
they’ve activated that prior knowledge. The term peer instruction was coined by
Harvard Physics Professor Eric Mazur. He’s also helped popularize this
approach to classroom engagement and has done some significant
research showing its effectiveness. It’s now a common instructional
practice across the STEM disciplines. Peer instruction is useful in many teaching
contexts, but there are other practices that leverage what we know
about prior knowledge. For surfacing students’ prior knowledge,
making it more visible to you and to them, you might give them an interesting problem
and ask them to brainstorm solutions and identify what they know or what they
think they know and what they don’t. You might have them write what are
sometimes called minute papers. Ask students to take out a sheet of
paper, maybe at the end of one class, and write down something they know about the
topic coming up in the next class session. Read through those minute papers between
classes, then you’ll have some idea of what to expect from students the next day. Doodling can also work to
surface students’ prior knowledge. Have them draw a picture or a diagram to
represent how they understand some topic or problem, maybe how blood
flows from the heart to the body. Then pass those doodles to
the front of the room. You can look through doodles pretty quickly
and get a sense of what they’re thinking. We shared a couple of ideas for activating
students’ prior knowledge already. Another simple strategy is to be explicit about
drawing on earlier material in your course. Let students know at the beginning of class which past topics will be
relevant to the day’s discussion. Analogies can help, too, relating new ideas
to concepts that students already know well. Although, as Michaela indicated, you want to make sure your students don’t have
the wrong analogy in their heads. And for some topics you can ask students to draw
on their personal everyday experience as a way to connect with more abstract course material. One last point, take a second and see if you
recognize what’s happening in this picture. This fellow is dropping Mentos breath
mints into a two-liter of Diet Coke. What follows is a fairly
dramatic geyser of Diet Coke. You may have seen videos of this
phenomenon before or even tried it yourself. A few years ago my daughter’s preschool had
a Science Day, where parents were invited to come to school and do science things. I was the Dad who brought in the exploding Coke. Even with five year olds once I had done the
demonstration they wanted to know why it worked. Now imagine doing this with a first-year
college Physics class, you could really get into the reasons why the carbonation
of Diet Coke produces this effect. Now consider two ways to use this
demonstration in the college class. You could spend 15 minutes explaining
the Physics of Mentos and Diet Coke and then do the demonstration or you
then provide them that 15-minute explanation. Which approach is likely to
engage the students more? And which approach are students likely
to better understand that explanation? Starting with the demonstration, then
providing the explanation after is an example of what Shorts and Bransford
call creating a time for telling. You’ve prepared students to want to hear