This is a meaning making approach to introducing equations. I will walk through the parts shown in the photo in the space below this photo. (A revised edition of this handout will be used in a video on this topic.)
First I explain the difference between an expression (no =) and an equation (has =). An equation is two expressions set equal to each other (21 is an expression).
I then develop the idea of a balanced equation and will refer to both sides of the see saw as a prelude to both sides of the equation. I also focus on the same number of people on both sides as necessary for balance.
At this point I am ready to talk about an unknown. Here is the explanation I use with the photo shown below.
- I start with the seesaw at the top. The box has some guys in it but we don’t know how many.
- We do notice the seesaw is balanced so both sides are equal.
- This means there must be 2 guys in the box.
- I follow by prompting the students to figure out how many guys are in the box(es) in the bottom two seesaws.
- Finally, I explain that the number of guys in the box is the solution because it makes the seesaw balanced.
There are multiple instructional strategies in play.
- Connection to student prior knowledge – they intuitively understand a seesaw. This lays the foundation for the parts of an equation and the concept of equality.
- Visual representation that can be recalled while discussing the symbolic representation, e.g. x + 1 = 3
- Meaning making which allows for more effective storage and recall of information.
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