Final answer:
Reading aloud with emphasis on 'ci,' 'ce,' or 'cy' words is an effective activity to reinforce this principle.
Step-by-step explanation:
An effective activity to use when reinforcing the 'ci,' 'ce,' or 'cy' principle is reading aloud with emphasis on 'ci,' 'ce,' or 'cy' words. By reading aloud, students can hear the correct pronunciation of these letter combinations and reinforce their understanding of these spelling patterns. For example, they can read words like 'circle,' 'celebrate,' and 'encyclopedia' with emphasis on the 'ci,' 'ce,' and 'cy' sounds.