Is this the first time your students hear about this date? Ask them and if this is the case, start from here. Let   students read the introductory passage to the lesson plan  and after reading it, ask them to answer the following question in pairs:

"Why is November the 25th the International Day for the Elimination of Violence Against Women?" 

Once students know about the ultimate goal of the international campaign to end  gender-based violence, tell them that you are going to focus on "Teen Dating Violence"Below these lines, I will be providing you with different activities for you to choose  depending on the number of sessions you wish to spend

One of the many ways to work on this topic is through interactive resources. A very powerful website is "That's not cool": it is dedicated to decreasing teen dating violence due to technology, and  increasing awareness for healthy teen relationships online. The same as in the previous stage, you can start with a question: "What is the difference between a healthy and an  unhealthy relationship?"  Ask them to brainstorm  ideas in pairs and represent them in a visual  way they choose. For example:

After sharing their concepts of healthy versus unhealthy relationships, tell them that they are going to play an interactive game called "Coolnotcool". This interactive  quiz engages teens in a dialogue about teen dating abuse by putting the power in their hands. By doing the quizz, students will review  some  fictional dating scenarios and  decide for themselves whether those interactions are ‘cool’ or ‘not cool.’ 

If you are into  Q & A, you can explore the Speak Up section from "That's not cool" and let students spend some time reading the questions and answers. Encourage them to take a stand on the issues and add a question to the list on the page. 

For those  of you who are ready to develop  some more sessions on this topic, which would be well worthwhile, this pdf contains several activities which will enable students to gain an insight into healthy relationships - the ultimate prevention against abuse.