Evaluating algebraic expressions
This sequence of tasks enables students to compare equations, inequalities, and identities (equivalent expressions) by various means. Substitution is used to find out when expressions are equal in value. It is more common in textbooks to use substitution merely as a means to practice using symbolic conventions, but here it has a role to play in understanding the underlying relations.
The tasks are designed to challenge common misconceptions about the relations between numbers and variables and unknowns.