1.)Say: "Today we are learning about variables and expressions. First, let’s go over some vocabulary." On the overhead, whiteboard, or interactive whiteboard, write the word VARIABLE. Ask the students to tell you what they think a variable is and either you or they write their responses on the board. See if there is a correct answer on the board. If there is, have the class take a vote of what they think the correct one is. If there is no correct answer, you write the correct definition: A VARIABLE is a letter that is used in place of a number. Students should then write the correct definition in their journals/notebooks.
Explain that sometimes in the directions the variable is given a value. This value will replace the variable in order to solve the equation. Other times, the variable is NOT assigned a value and the student is to solve the equation to determine the value of the variable.
2.)Say: "Our next word is ALGEBRAIC EXPRESSION" (write this word on the board). "Look at the word and notice that there is a word we already know--expression. Who can tell me what an expression is?" Allow students to respond. Make sure the correct answer is given: an expression is a number sentence without an equal sign. Now ask them what they think ALGEBRAIC EXPRESSION means and either you or they write their responses on the board. See if there is a correct answer on the board. If there is, have the class take a vote of what they think the correct one is. If there is no correct answer, you write the correct definition: An ALGEBRAIC EXPRESSION contains at least one variable, one number, and one operation. Ask them to recall what operations are. An example of an algebraic expression is n + 7. Students should then write the correct definition in their journals/notebooks.
3.)Write on the board the vocabulary word CONSTANT. Again, have the students give examples of what they think this means and either you or they write their responses on the board. Check if a correct answer is on the board. If there is, have the class take a vote of which one they think is correct. If not, you write the correct definition: a CONSTANT is a number that stands by itself. The number 7 in our previous example is a constant. Students should then write the correct definition in their journals/notebooks.
4.)Write on the board the vocabulary word TERM. Again, have the students give examples of what they think this means and either you or they write their responses on the board. Check if a correct answer is on the board. If there is, have the class take a vote of which one they think is correct. If not, you write the correct definition: A TERM is each part of an expression that is separated by an operation. For instance, in our earlier example n + 7 the terms are n and 7. Students should then write the correct definition in their journals/notebooks.
5.)Say: "Now let's identify each part of this ALGEBRAIC EXPRESSION: n + 7
What is the n?" (They should say variable.)
"What is the +?" (They should say operation.)
"What is the 7?" (They should say constant.) Students should label the parts of an algebraic expression in their journals/notebooks.
6.)Say: "There are times when an algebraic expression has a constant and a variable right next to each other WITHOUT an operation between them. When this happens the constant is not considered a constant. Why not?" (They should recall that the definition says it is a number that stands by itself.) "Since the number no longer is standing by itself and is attached to the variable, the constant is no longer a constant. It is now a coefficient. The definition for coefficient is a number in front of and attached to a variable. For example, in the expression 8x + 3 the 8 is the coefficient and the X is the variable and the 3 is the constant. Who can tell me why the 8 is the coefficient and the 3 is the constant?" Students should then write the correct definition of a constant in their journals/notebooks.
7.)Say: "For a quick review of what we learned today and so I can see what you learned, there is a short worksheet that you are to complete" (attached). Pass out one worksheet to each student. You can grade this as a quiz or daily grade.
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