I've noticed that most Spanish students find the use of say and tell quite difficult.
The reason is that their meaning is very similar in English but they are used in different grammatical constructions.
STEP 1: Try this exercise first to see how well you use these two verbs
STEP 2: If you've had problems, look at this interesting explanation
STEP 3: And now you are ready to repeat the first exercise again, to check if you have solved your problems and you are ready to progress a little bit more with the following activities:
Exercise 1
Exercise 2
STEP 4: I'd really be grateful to receive your comments about your experience with "say and tell" after doing the activities,
