The best way to introduce this concept to students is to ask them what a first-person narrative is. Most high school students are familiar with this term and will answer correctly. After getting a basic definition of first-person narrative that they all understand, define the idea of grammatical subject as the doer of an action – not the topic of a sentence. Give an example or two. Then define the first person as the person speaking in his or her own name – I. Next, ask them what they would guess the first-person plural is in English (we).
At this point, draw a grid on the board, one vertical line with two parallel horizontal lines crossing it at right angles and write I in the upper left-hand corner, labeling the left column singular and the right column plural. Write we in the upper right-hand corner, immediately to the right of the corner in which you wrote I.
The next step is to ask them what they suppose second person might mean. Depending on the group, you can almost always lead them to work from the person speaking of him or herself as the doer, as first person, to the second person being the person spoken to, as the doer of an action: you.
The next step requires paying special attention to their reaction in order not to lose any of them. Ask them what the plural of you is, in English. Of course, it is also you. Write you in the middle spaces, left and right, below I and we, respectively. Depending on how certain and secure they seem, you might ask them how two people talking to each other know whether you is being used to refer to only the one listening or to the person listening and others.
Continue in like manner, asking questions to elicit the correct definitions of third person – as the person or persons spoken of by another.
Label the rest of the paradigm in English and practice with a few English verbs in the present tense, being sure to point out that the third-person singular in English has a different form.
Finally, tell them that they are ready for some important news and tell them that in the Spanish present tense, verbs have a unique ending for each of the six persons. Tell them that making these endings match the subjects in the boxes is called subject-verb agreement.
At this point, you can either draw another grid and put in the corresponding Spanish subject pronouns or write them in the same boxes with their English translations. I prefer the latter.
The next activity can be done in five minutes or less. Tell them to tell you what the Spanish subject pronoun would be for a series of subjects, all by pointing: to yourself, to yourself and someone else, to someone you’re looking at, to someone you’re not looking at, but pointing to as you look at someone else, at two people you point at together and look at, etc.