When I start a new unit, I like to have some consistency, and I like activate prior knowledge, as well as let students know what is coming up and what the objectives will be. I have done this for the past two years by setting up a new title page in their notebooks. This title page has two sides (for the two pages of their notebook).
On one side is the objectives listed. I usually type these and give them a copy to attach. I like to give them a spot next to each to rate how well they know it, and to make notes as we go through the unit. I use a certain format for these, and I call them
"Keeping Track of Learning."
On the other side I have the students divide the page into four. In the center they write the title of the unit (which I give them). Then in each box they must draw a picture, with a caption, that is related to that topic. Depending upon the topic of the unit, sometimes I think that they may have some prior knowledge, and I leave it open-ended, except that I usually point them toward the chapter or section in the book where they can find additional pictures and inspiration. If I think it is a topic for which they won't have much prior knowledge, then I give them a list of maybe 4-8 main idea terms to choose from, and direct them to some resources.
I like this system because it gets them thinking about what they already know, and previewing the chapter (or other resources), without specifically being directed to do so. I provides a platform for them to discuss what they already know or what they think the upcoming topics will be about.
I usually take about 15-20 minutes in class, and I think its time well spent. Students get a chance to get their heads into what we are learning, and connect to it, and I get a chance to informally assess what they already know.
Here is an example photo:
I have also seen a teacher do a similar activity by creating a word cloud (such as from wordle) to include common vocabulary from the upcoming topic, and use that as a focus point or COVER image for the unit.