You have a large collection of 1 × 1 squares and 1 × 2 dominoes. You want to arrange these to make a 1 × 15 strip. How many ways can you do this? Start by collecting data. How many length 1 × 1 strips can you make? How many 1 × 2 strips? How many 1 × 3 strips? And so on. How are the 1 × 3 and 1 × 4 strips related to the 1 × 5 strips? How many 1 × 15 strips can you make? What if I asked you to find the number of 1 × 1000 strips? Would the method you used to calculate the number fo 1 × 15 strips be helpful?