This is a rich activity that prompts wonderful discussions between students, allowing them to see pattern growth and develop meaning for it.
One class period may not be enough time for this les-son, you may want spread it out over two lessons. Usually when growing cases are given out, they have the instruction: How many are in the 10th case or 20th case? with no discussion of the different visual ways people see the cases. But when students can share and discuss the different ways they see shapes, they develop meaning and understanding of the functional growth, that doesn’t come when students only focus on numbers.