We developed the following coding scheme to examine the extent to which teachers used academically productive talk moves (APT Moves) in their turns at talk to facilitate science discussions:

Teachers’ Facilitation of Science Discussions:

1. Expand Moves (Say More; Revoice; Wait Time; You-Repeat; Turn and Talk; Written Reflection): This set of moves was designed to encourage individual students to elaborate on their ideas (e.g., “Okay. Can you say a little more about that?”).
2. Listen Moves (Who Can Repeat; Who Can Explain): This set of moves focused on encouraging students to listen carefully to their peers’ ideas (e.g., “Ok, is there anyone who understands what Jasmine is saying and might want to maybe say it a different way to help the rest of us understand?”).
3. Press for Reasoning Moves (Why; Challenge; What If): This set of moves was designed to prompt students to push their understanding by digging deeper into their reasoning and providing evidence for their ideas (e.g., “Why? What is it about container A or the liquid in A that makes you think there’s not a lot in there?”; “How do you know it didn’t rise? Did you measure it?”).
4. Think With Others Moves (Add-On; Who Agrees/Disagrees): This set of moves engaged students to think with and respond to their peers’ ideas in fostering co–construction of their understanding (e.g., “Anyone want to, maybe want to revise Mario’s idea, maybe change it, add to it?”).

The coding scheme below was used to examine students’ turns at talk to identify the extent to which students explicated their thinking by presenting reasons and evidence for their claims, and made attempts to co-construct science understandings with their peers.

Students’ Scientific Reasoning and Co-construction:

1. Claim: A statement a student makes whose truth value can be tested or can be backed up with reasoning (e.g., “I think it was the volume that made the water rise”).
2. Reas-C: A complete reason which supports a claim (e.g., “Because it’s uh, bigger, it’s a lot more water than in that container”; “Because usually ice is made from frozen water”).
3. Reas-INC: An attempt at reasoning that is incomplete or unclear (e.g., “Because um, so that you like you wouldn’t waste like more time, using, using two containers and I think if you just put the um, the sandstone, ... I can’t explain it.”).
4. Revise: Evidence of revised thinking, marked by an explicit indicator, such as “First I thought X... (e.g., “Actually, I kind of changed mine cause I thought of evidence that if — I agree with Tomas now because, like, salt is — begins as a rock but after you slice it up into little minerals, they get lighter and lighter, and if you put ‘em in a wagon, they’d be much easier to haul up a hill.”)
5. Agree: Explicit marker of agreement with a previous idea (e.g., “I agree with Jasmine”).
6. Disagree: Explicit marker of disagreement with a previous idea (e.g., “Well I kind of disagree”).
7. Clarify: Clarification of someone else’s idea (e.g., “I think what she means is that when the temperature gets to like negative then things start to get cold [...]and it gets hard and then it just breaks like ice”).
8. Ask: Requesting clarification of a peer’s idea (e.g., “What do you mean when you say..?”).
9. Challenge: Challenge an idea, without an overt marker of disagreement (e.g., “ I have a question for you Frank. What if the eraser had like buoyancy?”).
10. Add-On: Student adds on to a previous idea, without an overt marker of agreeing, disagreeing, clarifying, or challenging (e.g., “Um I also wanted to add on to Louie’s...”).
11. What If: This move presents a thought experiment, often with imagined data (e.g., “How would we get the exact size of it? What if like, say, we made a model of Tomas’s.”).