Arrange which students makes which letter of the alphabet. The I and J have to be drawn on one sheet, to make a group work of five by five drawings.
Each student draws one big letter, with about 1 cm free space around. Colour the letter as you like, using patterns. Colour the background as well. Outline the letter and the details with a fine black marker. Make sure the letter 'pops up' from the background, by choosing different colours and patterns.
Paste all letters on a big black cardboard, five by five with 2 cm space between them.