Ultimately, the end goal of this project is that you relay what you've learned to others around you in a way that feels urgent, in a manner that is interesting (even if you have an important message but present it in a boring way --- who will care?) So much so that your message will impact them to make a change in their everyday lives, however small it may be.
But you can't do that unless you have chosen a topic that you are passionate about. One in which you feel like the world cannot live without! That is your starting point --- everything else will fall in line after you've selected the topic.
While there is writing involved in this project, let the focus of what you're going to use to teach people be the media component. Whether you use a podcast or an infographic to disseminate the information, it needs to be visually appealing or attention-grabbing, using whichever medium you choose.
The chart below breaks down the various components so you can see at-a-glance which portions could be done collaboratively, and which components will be done in your Language Arts vs. Science classes.