Phase:  Before/Engage 
Activity:  Begin by explaining to the students that today they will be learning about how to use letters in math. When we use a letter to represent a number in math, it is called a variable. If students are using math journals, they can write the word variable and define it. Explain that it's more common to use lowercase letters for variables and that any letter can be used as a variable.
Display the slide with the food images. Ask a student to pick two items she might want to order. For example, the student might choose a burger and a hotdog. Write a lowercase "b" under the burger and a lowercase "h" under the hotdog. Write the expression "b + h" and explain that this expression represents what the student ordered. Continue this procedure, allowing students to pick items and write the expressions using the appropriate variables.

Assessment Strategies:  Evaluate student understanding through questioning during the activity. Observe to see if students are able to use variables to write an expression to represent the meal they've ordered and if they can solve the equations by substituting the correct values for the variables.
At the end of the activity, you can place an order out loud for all of the students to solve independently as an exit ticket. For example, you might say, "I want to order 2 burgers, a hotdog, and a taco." The students should write "b+b+h+t" and calculate the total price of the meal. 
Advanced Preparation:  You will need a projector and board to display the slide. To label the items and write the expressions, you can use a board with the appropriate technology or chart paper taped to the board. You can also enlarge the images and then print and tape them to a dry erase board. 
Variation Tips (optional):  
Notes or Recommendations (optional): 
Keywords and Search Tags:  equation, expression, variable 