 Expression Tutor

### Activity Sequence: Elementary Algebra

This is as an illustrative example for how Expression Tutor activities could be used in a middle school algebra course. The page only provides a short, largely incomplete sequence of activities. If you are interested in using Expression Tutor activities to teach elementary algebra, please contact the Lugano Computing Education Research Lab.

Elementary algebra can be difficult to understand for students. Expression Tutor activities allow students to break down complex Expressions into smaller pieces, and to consider the smaller pieces in isolation.

#### Arithmetic Expressions

Arithmetic expressions deal with specific numbers (in programming languages, we call those "literals").

Below is a tree representation of the above expression. The tree consists of three green nodes. The top node, with the star, is the "root" of the tree. It represents the addition operation we want to perform. The two nodes below that represent the two numbers we want to add. The blue labels represent the values. The node 12 has the value 12. Kind of trivial, but that's how it is. The root node at the top has the value 15, because it represents the result of adding the values of its two children (12 and 3).

#### Algebraic Expressions: Variables

In algebraic expressions, some values are not known a-priori and are instead represented by letters (variables).

Below is a tree representation of the above expression. The node x represents the variable. Assume that the variable `x` has the value 10. Then the blue labels above each node show the values of the corresponding subexpression.