Unit 3: Reasoning and Explaining (MP2 and MP3)
3.3.3 Definition of “Rule”
Three groups of students in the classroom demonstrated misunderstandings when asked to define what a mathematical "rule" was.
Their confusion was influenced by everyday experiences with school rules and expectations. For example, one group explained that an example of a rule was that you couldn't play tag on the cement because it is easy to get hurt. However, they explained, there are exceptions made to the rule for physical education classes.
In the following video clip, Leslie similarly explains exceptions to rules. The notion of exception allowed students to see 9 as a multiple of 2 as an exception to the rule of even.
Teachers may assume that students understand that a mathematical rule is a statement that is always true. The definition exercise demonstrated that in the daily activities of students, rules often have exceptions.
In your Metacognitive Journal, consider how you would help students understand what "rule" means in mathematics.

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Mathematics: Kindergarten through Grade Twelve (K–12) Standards for Mathematical Practice. Brought to you by the 

