1. Warm-up Conversation. How are these processes similar and different for you and fungi? Teacher focuses students on connections between human biological processes and fungi biological processes and re-orients students to the extracellular digestion and cellular respiration model
2. Preparing students for round 2 investigation with yeast. Teacher uses a whole-class pre-discussion linking typical experimental design conversation with a discussion about the extracellular digestion à cellular respiration model. She asks:
   • What would you learn from changing temperature? Which part of the process will be affected? Think through the whole equation.
   • What will we be able to see?
   • What would you learn from changing amount of food? Predict what will happen if it has too many carbs or too few?
3. Choose an experiment. Students work with groups to select one question to investigate.
   • Do yeast have to go through extracellular digestion to produce energy?
   • How does temperature affect digestion and energy production?
   • What happens if yeast have too many or not enough nutrients?
4. Hypothesis writing. Teacher makes rounds to groups to help design experiments and craft rich hypotheses about how the experiments will test and inform parts of the digestion respiration combined model
5. Warm-up Conversation. On Day 8 the teacher leads a whole-class conversation about predictions from each of three experiment options. Teacher compares similarities and differences between groups doing the same experiments and presses students to define which part of the model they are testing (extracellular digestion, cellular respiration or both).
6. Revising hypotheses. Teacher presses students to use ideas from the digestion respiration combined model to elaborate their initial predictions by adding unobservables to their tentative explanations. Students are asked to circle these words in their hypotheses.
7. Applying models to evidence. The teacher visits each group during data collection to press students to relate what they are seeing to the big ideas within the model.

Discussion Questions: 1) For days 7 and 8 choose 1 line of experimentation--temperature-option 2 or starch vs. sugar-option 1--and track how students language about the experiment and the big ideas changed. 2) Make a list of 4 or 5 productive back-pocket questions Janet asks and describe how or why each was productive in revealing student thinking.