To add a level of difficulty. I would add number cube to see how many letters to cover up at a time. Use tally marks, dots, numerals ect Free "find the letter" alphabet worksheets! Get them for uppercase, lowercase, and both!
Free Alphabet Letter of the Week is designed to help teach letter A for children who are learning their letters. This set contains pages of variety activities, games and worksheets. Preschool Worksheets Kindergarten Worksheets First Grade Worksheets