One of the first phrases beginning students of Spanish are taught is "Me llamo ___". At first, it is presented almost as a vocabulary item so that students can introduce themselves and exchange greetings, but soon they'll need to know what they are saying and why "Me llamo es ___" is so wrong!
Now and then there is a physical prop that speaks volumes about a grammar concept, but a mirror is has to top the list when it comes to teaching reflexive object pronouns. This lesson plan is particularly useful for high schoolers or even junior high students.
Begin by writing the subject pronouns on the board, in the familiar six-hole paradigm, to the left. Next, skipping enough space to its right for the reflexive object pronouns, write vertically a list of verbs, conjugated at random in various persons and numbers. Be sure to pick verbs that are reflexive or have the capacity to be so: lavar, llamar, ver, lastimar, caer, bañar, and so on.
Before introducing the reflexive objects, have students identify the subject pronouns from the chart on the left that are or could be the subjects of these verbs. If they seem rusty or unsure, add more verbs or change the conjugations of the ones you have written. After they seem confident with identifiying the subjects, ask them what the various phrases mean, as written, e.g. [yo] veo = I see.
Next, review direct object pronouns by writing a list of nouns and pronouns in the blank area: yo, revista, lápiz, carro, nosotros and tú. Tell them to convert these nouns and pronouns into direct object pronouns. Once they have answered (me, la, lo, lo, nos and te), have them form sentences using various forms of the verb ver. Write various conjugations of ver on the board. Be sure to include veo, ves and vemos, but use a pointer to direct them to the direct object usages only -- in other words, avoid the combination me veo, te ves and nos vemos until the very end.
When you have covered the direct objects combinations well and they are comfortable, erase all but the ones that will produce reflexive usages, but don't start with them. Start with te vemos, nos ves, and get them to tell you what these mean (we see you and you see us, respectively).
Finally, pause and point out the reflexive combination me veo and ask them what they think it means. As you do so, hand the person whom you pick to look into the mirror as he or she answers. From this point, the concept can be explicitly addressed. Tell the students that they are now going to learn reflexive object pronouns and that in fact, they've already seen three of them. Write them on the board, reminding them that me, te, nos and os (if you teach vosotros forms) do multiple jobs as various types of objects. Point out that the third person is where they will see the different forms and that they must be very attentive to them, se being the third-person reflexive object pronoun for both singular and plural.
Finally, ask them to translate me llamo -- as distinct from what it means, i.e., I call myself. Then proceed with a number of phrases in Spanish, then English, at random, orally and have them translate them into the other language. Classes with younger students can also be divided into teams with short lists of such phrases. The first team to correctly translate their phrases, writing them on the board, wins.