4-Story Tower Activity

I tested the 4 tower lesson on a friend. For this activity I gave my friend a total of 100 connecting cubes; 50 yellow and 50 green. The directions were to create as many different 4 story towers combination using two colors (no pattern can be repeated). Immediately, he stated 4X4=16; there are 16 total combination. I asked him to show me using the connecting cubes and prove he is correct. He began to make various patterns. When he said he was done I asked what his strategy was? He stated: First he took three of the yellow and one of the green and worked his way down and up (total of 8 story-tower). Next he created two solid towers of one color (total 2 story-tower). Last he mixed it up two and two of each color (total 6 story-tower). Creating a total of 16 combination.

(Picture describes method from right to left)