I created many French secret messages as an enrichment activity in math for my strong students. I used them after tests or projects as a sponge activity but it may become a fun way to practice basic operations at home. I successfully used these activities in grades 2-6 French Immersion.
Students should perform addition/subtraction in order to find a value for every letter of the message. When all the values are found, students will be able to read the message. It is usually a funny request, like “draw a rocket ship with 3 aliens” or “create symmetrical pattern with pattern blocks”. The answers appear on your PDF when you roll over your mouse. They will not appear in print.
I hope this activity will motivate your students to practice.