Stanford University Solar Center
Learner Objectives:
After the activity, students/participants should understand that:
1. The Sun produces light in all wavelengths, including invisible ultraviolet (UV)
2. UV can be dangerous and can burn our skin, damage our eyes, and destroy our cells.
3. The Earth’s atmosphere provides significant, but not complete, protection from UV.
4. There are both ways to detect UV and also to protect ourselves from it.
Obtaining UV beads:
You can purchase UV beads from Educational Innovations™ or a similar source:
http://www.teachersource.com/product/ultraviolet-detecting-beads/light-color
When gathering beads, 1 large coffee scoop holds ~75 beads. Warm temperatures help the beads
change from white to colored. Cool temperatures, e.g. ice water, help the beads return quickly to white.
Note: Some older sunscreens do not work with these beads, nor do they work with human skin. Newer
sunscreens have corrected this deficiency.
Background:
These beads contain a special chemical that changes color when exposed to ultraviolet (UV) light. UV
is an invisible type of light from the Sun. It can burn our skin and cause cancer, damage our eyes, and
destroy our cells. Most UV is blocked by our Earth’s ozone layer and atmosphere, but some still gets
through and can be detected. The beads will stay white when inside or not exposed to UV.
Incandescent and fluorescent lights will not affect them. They will only turn bright colors when
exposed to UV, usually from the Sun or a UV (“black”) light. The darker the color of the beads, the
more UV rays they are detecting. Once you bring the beads back indoors, they will (slowly) change to
white again. This process can be repeated many times. (Further information on UV is provided with
the EM spectrum image.)
Process:
1. Paraphrase the description above and show participants the electromagnetic spectrum chart. Ask
them if they understand that there are more forms of light than what we can see. Can they give
examples [X-ray, radio waves, etc.]? Reinforce the concept that ultraviolet (UV) is a form of light
that cannot be detected by our eyes but is emitted by the Sun and other stars.
2. Hand out beads and pipe cleaners, and bookmark materials if
you wish to make them. Have participants assemble their
bookmark, if necessary. Then have the students string their
beads onto the pipe cleaner or ribbon, put it through the hole in
the bookmark, and twist or tie the ends together.
3. Now, ask the students to be the scientist and experiment
with their beads! Hand out the worksheets and have
participants determine which materials keep the beads, and