Each group needs:

• 2 filled and sealed carbonated beverage cans, such as cola or lemon-lime soda
• (optional) 1 timer, to measure 30 seconds or less; alternatively, students can use the second-hand on the classroom clock
• 3 identical 150-ml glass beakers; note that other-sized beakers, columns, graduated cylinders, small rectangular prisms, test tubes, etc., will also work—just make sure the containers are identical (for each group), each hold 100 ml of fluid and are large enough that students can drop a marble into each  
• 3 marbles or small objects that can be dropped into the aforementioned containers; as an optional extension, make available additional small objects of differing size, mass or density to provide for additional experimentation
• 100 ml each of 3 fluids with varying viscosity; prepare the solutions in larger beakers (such as 250 ml or larger) and pour them into the 150 ml beakers; for example, consider using water and corn syrup combined in varying proportions by volume, such as:
• 100 ml corn syrup
• 50 ml corn syrup and 50 ml water
• 120 ml corn syrup boiled down to 100 ml to create more viscous corn syrup
• 3 plastic drinking straws, such as a 100-pack for $7 from Ikea/Amazon
• 3 glass stirring rods
• Viscosity and Pressure in Volcanic Eruptions Worksheet, one per student

To share with the entire class:

• (optional) projector to show the Volcano Presentation, a PowerPoint® file