Activity 3.1 - Predictions about Soda Water Fizzing (20 min)

Target Performance

Students develop hypotheses about how matter moves and changes when soda water loses its fizz and make predictions about how they can use their investigation tools—digital balances and BTB—to detect movements and changes in matter.

Resources You Provide

  • Petri dish, plastic (1 per class)
  • Soda water (1 cup per class)

Resources Provided


Print one copy of 3.1 Predictions and Planning Tool for Soda Water Fizzing for each student. Prepare a computer and projector to display the PPT.


1. Use the instructional model to show students where they are in the course of the unit.


The Matter Movement Question and Matter Change Question will be new to students, and Level 2 students will find the questions themselves hard to understand. Note whether students use the “Facts about atoms and molecules” that they studied in Lesson 2 as they try to answer the Matter Movement and Matter Change questions.

  • Rules to follow: The most important rule (and the first Fact about Atoms) is: Atoms last forever. Do they follow that rule when they try to answer the questions?
  • Evidence to look for: Students will address this column in more depth when they do the investigation. One thing to note for now: When students see gas bubbles leaving the soda water, do they cite that as evidence that atoms are leaving the soda water? Do they suggest ideas about what gas might be in the bubbles? Note whether students connect bubbles leaving soda water with atoms leaving soda water.



  • Have a designated place in the classroom where students store their Predictions and Planning Tool so they can easily refer back to their ideas at the end of the lesson.

Expect many students to make the right predictions for the wrong reasons. Note in particular whether they say that changes in the mass of the soda water indicate that atoms are moving.

Extending the Learning

Extending the Learning
Students can discuss other situations where bubbles form and leave liquids, such as the bubbles that form when water is boiled, when baking powder or Alka-Seltzer are dissolved in water, or when vinegar and baking soda are mixed. How do they see these phenomena as similar to or different from soda water fizzing? What do they see as happening to mass?