Part 1: Engage (Anchoring Phenomenon)

Phenomenon: Every spring in New England, sugar makers collect sap from sugar maple trees. The sap looks and tastes mostly like plain water. To turn it into thick, sweet maple syrup, they must boil it for hours in large pans over roaring fires. It takes about 40 gallons of sap to make just 1 gallon of syrup!

Questions:

  1. What is physically happening to the sap as it boils for hours? Where is all that volume going?
  2. Why do you think the sugar makers need such a large, hot fire to make the syrup?
  3. How do you think the concentration of sugar in the liquid changes as the boiling process continues?

Part 2: Explore (Simulation Investigation)

Access the simulation: Connecticut Maple Syrup Thermodynamics

Investigation Instructions:

  1. Start the simulation. Observe the initial state: What is the starting sugar concentration? What is the current temperature?
  2. Use the heat control to increase the burner to maximum heat.
  3. Monitor the temperature graph. At what temperature does the water begin to boil?
  4. Once boiling begins, watch the “Sugar Concentration” gauge. Record the concentration every 30 seconds for the next 2 minutes.
  5. Observe the “Water Volume” and the “Energy Added” counters. What happens to the water volume as energy is continually added to the boiling sap?
  6. Try lowering the heat to a medium setting. How does this affect the rate at which the sugar concentration increases?

Part 3: Explain (Sensemaking)

Using your data and observations from the simulation, answer the following questions:

  1. Energy and Phase Change: The temperature of the sap rises steadily until it reaches the boiling point, but then it stays relatively constant even though the fire is still adding heat energy. Where is that heat energy going, and what is it doing to the water molecules?
  2. Concentration and Rate: How does changing the heat input (temperature) affect the rate at which water evaporates? How does this evaporation directly affect the concentration of sugar in the remaining liquid?
  3. Collision Theory connection (Extension): Think about the particles of water in the sap. How does adding heat energy change the behavior of these particles, and why does this result in the liquid turning into a gas faster?

Part 4: Elaborate/Evaluate (Argumentation & Modeling)

Task: Construct a scientific explanation detailing the physical processes required to turn raw maple sap into maple syrup.