Substituting Numbers for Letters

Make a Train

Work Time

Make a Train

  • Use the Creating Trains interactive to make a train that has at least 8 cars. The table shows the types of cars that you can use to make your train.
  • Write two different expressions that represent the length of your train. Use the letters specified in the table to represent the lengths of the different types of cars.
  • Find the length of your train by replacing the letters in each of your expressions with the values given for each letter in the table. INTERACTIVE: Creating Trains


  • Did you make a train and write an expression for the train?
  • Did you replace each variable in the expression with the appropriate car length from the table?
  • Once you complete these steps, you can calculate the length of the train.