It is my experience that students think that making inferences is simply guessing. I guess it is, to a degree, but it's an educated guess--kids have to have background knowledge in order to make an inference.
I teach it as an equation:
Text + background knowledge = inference
For this Guiding Question, students are asked to give me their definition of an inference. Most of the time, they are going to tell me that you can infer when you read, but really we infer all the time!
I've been collecting powerful images since I've been teaching, and I've done a number of different things with them. I highly suggest getting a lot of images like this (mine mostly came from National Geographic and Smithsonian magazines), laminate them and keep them around for a rainy day.
Here are some of my favorites, though the ones I have are cut from magazines, numbered, and laminated:
For this lesson, I hang the pictures all over the room and tell the students to "take a gallery walk." This is to act as though they are in a museum, to keep talking to a minimum and a whisper, and to just notice. I don't give them any other assignment at first, than to just look.
Next, I give them the Inferring chart and have them choose three of their favorite pictures to "read." They jot down the picture number, give me some background knowledge, and make an inference. Sometimes they'll claim they don't have any background knowledge--see my Reflection for what I do when this happens.
When we are done, we have a time of sharing out, and I'll either tell them the story of the picture (to the best of my ability), or we'll make an inference together.
Lastly, we transfer this skill to text. I give them the first paragraph of the Inferring passage and ask them to make an inference--reminding them that an inference is text + background knowledge.
To reinforce this skill, during their Independent Reading for the following week, I ask that they are cognitive of their inferences. As I confer with them, I'll be asking for the inferences they've made while reading.