Directions 1. Use the instructional model to show students where they are in the course of the unit. Show slide 2 of the 2.3 Home Groups: Share Expertise PPT. 2. Explain the purpose of the activity. Tell the students that it is their job to discuss the four considerations (generalizability, representation, and short-term/long-term) for each of their phenomena with the rest of the group. You can review these concepts using slide 3. Have students retrieve their 2.1 Finding Patterns Tool for Earth Systems. At this point, only the first row should be completed (for Arctic sea ice). Give the students the following instructions: First, show slide 4, have experts from Group A will have 10 minutes to explain their phenomenon to the other members of the home group. It is the experts’ job to lead a discussion about what they learned in their expert group. When Expert A is discussing the phenomenon, other members should ask questions if they don’t understand something. After the discussion, the group should complete the row for Group A’s phenomenon, with the exception of the final column. Ask the students if they have any questions about what they should be doing. 3. Give “Expert A” 10 minutes to explain a phenomenon. When Experts A are explaining, circulate around the room. Encourage group members to ask questions about what they don’t understand. Use this time as formative assessment to determine what they still may be struggling with in terms of generalizability, representation, short-term variability and long-term trends. If you see students struggling with different ideas across groups, pause the discussions and see if you can resolve the issue as a whole group. 4. Repeat steps 2 and 3 for Experts B, C, and D using slides 5, 6, and 7, respectively. 5. Have students overview the “four considerations” for each expert group data. Show slide 8. Tell students that as a group they should try to summarize the “generalizability” and “representation” and “short-term variability” and “long-term trends” for each phenomenon. Circulate the room to see which of the “four considerations” they may be having trouble with. Tell them to use their Arctic sea ice column on the first page as reference if they are struggling to complete the tool. Tell students to leave the far-right column blank. They will complete that in the next activity.