density Hypothesis particle model particles
Age Group
11 12 13 14
Expected time
1 period
The chi wheel.PDF
beaker symbol

The chi wheel

What’s the mystery? Can people really move objects through the power of their mind? In this lesson, students witness the amazing chi wheel, which claims to work by focusing chi energy. Students test hypotheses to obtain scientific explanations about how it really works.
Domain(s) Physics
Subdomain keywords Hypothesis, particles, density, particle model.
Age group 11 to 14 years old.
Expected time for the mystery Approximate time for teacher preparation: 15 min.Approximate time in classroom: one 50-min lesson.
Safety/supervision Students need to be careful when using hot water. Be aware that spillages may occur and that the floor may become slippery, causing a hazard.Disclaimer: the authors of this teaching material will not be held responsible for any injury or damage to persons or properties that might occur in its use.
Preparation and list of materials For teacher demonstrations:

A piece of paper around the size of a post-it stamp, an eraser, needle, or pin to make a chi wheel. For instructions, search for ‘psi wheel’ on the website ‘Wikihow’.

Water balloon filled with cold water (keep this in the fridge before using), bowl, cold water from the tap, warm water.

Each small group of students will need:

Large beaker of cold water, 4 polystyrene cups, hot water, food colouring, disposable pipette.

Learning objectives Students will describe how the spacing of particles changes as a fluid is heated and use this to explain why hot fluids rise.