Spanish interference with proper English message transfer.

[EDGARMR]

Hi, I'm new to the forum but I felt I needed some help with this issue. Maybe some of you out there have had this type of situation before. I teach English in Mexico. There is a big community of English language learners here and I have noticed that most of them have the same issue at some point in their learning process.
A lot of times students will say someting like the following: "eat at three."
Now that isn't an imperative sentence. That is their way of saying "I eat at three."
What I have come to notice is that since in spanish the subject and the verb join, as in "corro" (I run), a lot of my students will omit the subject when speaking or writing due to this L1 interference.

What strategies can I use to drive home the idea that the subject needs to be present in a sentence.
I have resorted to speaking drills and writing exercises, they do show some effectiveness while we work but days later that same issue pops back up. I know it isn't something that will stick right away but I can't help but feel that I could probably be trying other strategies.

If anyone has some ideas based on their experience I would really appreciate the help.

[kdammers]

(This is) Only for students willing to voluntarily use it:

The student puts a loose rubber-band around the ono-dominant wrist. Then when-ever s/he omits the subject, s/he snaps the rubber-band, creating a minor irritation. A teacher can help by, e.g., pointing to the wrist when the error is made. I have used this with a small number of students (but not with Your specific problem), and it has mostly worked.

[kdammers]

Here is an unconventional trick that a learner can use if willing: put a rubber band around your wrist. Any time you find yourself making the given mistake, snap the rubber band. A few of my adult students have used this technique. (I want to be clear that the only person who may snap the rubber band is the person wearing it.)