C2. Equations and Inequalities:
demonstrate an understanding of variables, expressions, equalities, and inequalities, and apply this understanding in various contexts
identify quantities that can change and quantities that always remain the same in real-life contexts
24 hours in a day
number of hours spent playing
12 months in a year
number of months until a special event
number of cents in a dollar
number of cents to buy something
number of wheels on a tricycle
number of tricycles
Throughout the year, where possible, address the concept of variability by identifying quantities that stay the same and quantities that can change. For example, when students are working with time, they can identify the elements of time that are always the same, such as 24 hours in a day. Then discuss how this is different from the number of hours in a day they might play, because the number of hours they might play can change from one day to another.
determine whether given pairs of addition and subtraction expressions are equivalent or not
Provide students with a variety of addition and subtraction expressions, and have them represent the expressions using a number balance. Have them track which expressions are equivalent and which are not.
identify and use equivalent relationships for whole numbers up to 50, in various contexts
Ask students to represent numbers in a variety of ways using manipulatives (e.g., buttons, beads, sticks, relational rods, tiles), and ask them to explain how their representations of the numbers are equivalent.
When students are developing a math fact, such as 3 + 5 = 8, ask them to show that when the addends are reversed, the sum is the same, that is, 5 + 3 = 8.