2019
Name: ______________________________________ Date: ________________________
Student Exploration: Half-life
Vocabulary: daughter atom, decay, Geiger counter, half-life, isotope, neutron, radiation,
radioactive, radiometric dating
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Have you ever made microwave popcorn? If so, what do you hear while the popcorn is in
the microwave? Popping kernels.
2. If you turn the microwave on for two minutes, is the rate of popping always the same, or
does it change? Explain. It depends on if it just started or at the end of its cycle.
Gizmo Warm-up
Like an unpopped kernel in the microwave, a radioactive
atom can change at any time. Radioactive atoms change
by emitting radiation in the form of tiny particles and/or
energy. This process, called decay, causes the
radioactive atom to change into a stable daughter atom.
The Half-life Gizmo allows you to observe and measure
the decay of a radioactive substance. Be sure the sound
is turned on and click Play ( ).
1. What do you see and hear? the kernels popping gently popping
Note: The clicking sound you hear comes from a Geiger counter, an instrument that detects
the particles and energy emitted by decaying radioactive atoms.
2. What remains at the end of the decay process? A daughter atom
3. Is the rate of decay fastest at the beginning, middle, or end of the process? At the beginning
Activity A:
Decay curves
Get the Gizmo ready:
●Click Reset ( ). Be sure that User chooses half-
life and Random decay are selected.
●Check that the Half-life is 20 seconds and the
