• Objective: Investigate how carbon dioxide affects photosynthesis.

  Did you know? 🤔 Pondweeds like Elodea can produce oxygen bubbles when they photosynthesize!

• Steps

  Note: Please don't throw non-native pondweeds into local water bodies! 🌍

  • Boil & cool water to remove gases, especially CO₂.
  • Shuffle that water between beakers to oxygenate it.
  • Put a cut stem of pondweed in the water (no bubbles should form).
  • Add sodium hydrogen carbonate to up CO₂ concentration.
  • Count bubbles for 30 secs.
  • Increase CO₂, repeat counting.
  • Continue until more CO₂ doesn't affect bubble production.

Questions to ponder: - Why boil water? And why light it up? - How to make this bubble count more precise? - What other factors might affect photosynthesis?

• Objective: Discover how light affects photosynthesis.

  Fun Fact: 🍃 Leaf discs can photosynthesize for hours if kept in the right environment!

• Steps

  • Use a syringe with sodium hydrogen carbonate solution (source of CO₂).
  • Add 10 leaf discs.
  • Remove air from leaf discs (they should sink).
  • Shine light, and watch them rise (due to oxygen production).
  • Record time taken for each disc to rise.
  • Measure light intensity & change light distances.
  • Plot results on a graph.

DIY Tip: You can use a cork borer or the end of a straw to get those leaf discs. 🍹

What’s a Hypothesis? 🧪 It's a testable prediction. It could be based on theories or past experiments.

Remember!: - Dependent Variable (Outcome we measure) - Independent Variable (What we change)

Pop Quiz! Which is dependent and which is independent?

• effect & cause
• what you observe & what you change
• y-variable on a graph & x-variable
• carbon dioxide absorption & humidity
• oxygen produced per hour & number of chloroplasts
• time to solve a math problem & gender