creativity and planning

So tomorrow is the first pro-d of the year and I get to spend the majority of my day planning for the coming year. One of my focuses will need to be on incorporating ways for children to express themselves in creative ways. I know very little about "art" officially, but am beginning to realize that art has very little to do with encouraging creativity with children. It is definitely a worthy component of it, but it is not the only, or maybe not even necessarily, the best way.
For example, the other day in math class, the topic was patterns. We talked about what a pattern was (something that repeats), saw some examples of patterns and then I let them create patterns. I took out blocks, lego, cars, chain links, etc and let them build a pattern. It was fun to watch them be creative. The teacher's guide said I should limit them to a repeating pattern of 2, but I have some fairly bright children in my class and didn't want to limit them. Some children
did indeed build repeating patterns with two colours and I was thrilled that they "fully met expectations." However, some children became much more elaborate. One particular boy built a pattern in 2 ways. He found 3D shapes of different colours and did a pattern of first 4 shapes (cone, cylinder, pyramid and cube [he actually knew these terms!]) in all the same colour and then repeated that pattern in the next colour and on and on. I was amazed. Would he have been able to express his creativity if I had kept him to two colours? I don't think so, and I was able to assess his learning as "beyond expectation." How exciting!