A similarly short and exemplary text should be concocted to add to the page. Pass it on. When you can read these words, know that you have made us very happy. We now ask you in return to give the same gift to others by teaching them what you have learned. For this we thank you.
Students just have to infer each sound from the pictures.
Fortunately the pictures implicitly contain the information that some are consonants and others are vowels, so this may be unnecessary. That one sentence may be enough to eliminate this problem. Refine it as needed. Publicize it and get it into the hands of every illiterate Tamil speaker in India and Sri Lanka. Send it to every charitable organization and ask their help.