Mystery Balloon Pop
Subjects and Target Audience: 5-8, and can be modified 9-12.
Duration: 60 – 90 minutes
Brief summary:
Students work in pairs to explore how a magnifying glass can be used to pop
balloons! They will also explore whether the color of the balloon matters! White
balloons reflect light whereas dark balloons absorb light and pop more readily.
Students can explore how different colors respond to converging light rays as
well.
Materials:
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Black and white balloons
Colored balloons
Magnifying glasses (one per group)
Sunlight (mother nature)
Stop watch (optional – most students have)
Tips to restock the kit: Most dollars stores (and high school science labs) have the materials required for
this activity.
Step-by-step procedure:
A. Introduction (10 mins)
The volunteer asks the class several open-ended questions such as the following:
 What is light? (A: Photons of energy that travel in a straight line at high speed; comprised of
different wavelengths. The visible spectrum represents a very, very small fraction of the
overall light spectrum)
 What color is light from the sun? (A: white)
 How does a converging lens work? (It bends light rays – refracts them – to a common point
called a focal point. The light rays bend because glass is a different material than air, and the
light rays travel at a different speed through glass. This is why they bend).
 Is this the same as a magnifying glass, or different? (A: the same)
 What types of materials absorb light? (A: darker materials – these absorb more light)
 Why does your shirt look black or white or yellow? (A: We see the wavelengths of light that
are reflected or put another way, not absorbed).
B. Volunteer introduces the activity (10 mins). Depending on the number of magnifying lenses and
balloons available, the volunteer forms groups. Pairs are great for this activity. The challenge is for
students to inflate a white balloon to full volume, and then inflate a black balloon within the white balloon
to about ½ the volume of the white balloon. The volunteer can prompt how to do so if desired – but
perhaps best to let the students explore. Pairs then, on a sunny day, harness the energy from the sun in an
attempt to blow up the balloons. They soon discover the internal black balloon explodes while the white
balloon remains in tact. Students are encouraged to record the precise amount of time required to explode
the balloon.
C. Activity I (20 mins): In pairs, students perform the activity.
D. Volunteer introduces activity II - optional (10 mins)
Students can inflate single balloons of different colors, ideally spanning most of the major colors
(ROYGBIV). Students record the time record to explode each balloon in their notebook, and on the class
table on the board that the volunteer creates (see sample below). At the volunteer’s discretion, the
students can copy down the table on the board, and for homework, determine class averages and range for
each color set.
Note: students must try to perform experiments in a reproducible way (e.g., inflate balloon to same
approximate volume, and most importantly, be consistent in forming a focal point). The latter can be
achieved using opaque paper. The volunteer can demonstrate this.
E. Students do activity II, again in pairs (20 mins)
F. Class wrap-up and open discussion of findings and student interpretations – 10 minutes
Review that the color of the balloon matters. White balloons reflect light whereas dark balloons absorb
light and pop more readily. Review how different colors respond to converging light rays.
What’s happening (scientific explanation; resource: stevespangler.com):
This activity demonstrates just how powerful the sun's rays can be! When you use a magnifying glass to
focus the sun's rays to a focal point, you create a spot that is incredibly hot. It is the perfect way to start a
fire (literally). That is how hot that dot of light can get! It is no surprise, then, that this immensely hot
light pops a balloon, but why is only the black balloon popped?
Luckily, for the clear balloon, most of the light and its heat, pass right through the balloon's surface.
You've seen this in action before. When you look through glass windows, a clear drinking cup, or even a
pair of glasses, you're witnessing light passing through a surface. Since the clear balloon is nearly
transparent, the same thing happens when it is exposed to light, even in a high concentration.
The black balloon is not so lucky. When we're talking about light, black is created by a surface that
doesn't reflect any light… it absorbs almost all of it. This "absence" of reflected light creates the black
color we perceive. With a surface absorbing all of that light, it also absorbs the energy. In this case, that
energy is heat, and a lot of it. The heat absorbed by the black balloon from the focused sunlight quickly
causes the bonds of the balloon to weaken until it can no longer contain the air on the inside. The
pressure from the air is just too much as it explodes, releasing the air into the clear balloon.
Supplemental resource / reference: http://www.stevespanglerscience.com/lab/experiments/mysteryballoon-pop
Supplemental instructions for volunteer to inflate both balloons in one:
 Blow up the clear balloon, but do not tie off the open end.
 Partially insert the black balloon into the clear balloon. Make sure the opening to the black
balloon is still accessible.
 Blow up the black balloon until it is about half the size of the clear balloon and tie off the black
balloon. Once tied off, push the black balloon the rest of the way into the clear balloon and tie
off the clear balloon.
 Use the magnifying glass to focus sunlight on the black balloon inside. The black balloon
pops!
Detailed activity:
This activity is designed to give students hands on experience using a converging lens (i.e., a magnifying
glass) to form a focal point on a balloon in an attempt to blow it up! Students examine how white and
dark-colored balloons have different sensitivity to converging light rays from the sun. The first activity
has students inflate a white balloon to full volume, and subsequently, to inflate a black balloon to half
volume inside the white balloon. Students then target light from the sun using a magnifying lens onto the
inner black balloon in an attempt to pop it. The black balloon inside the set-up explodes while the white
balloon remains in tact (hopefully). As an extension activity, students can explore how long different
colored balloons require to explode. The class can tabulate results in a table (see below) and discuss
findings.
PLOs and Achievement Indicators, Grade 8:
Physical Science:
Optics:
 C1, Demonstrate knowledge of the behaviour of waves
 C2 explain the properties of visible light
o Identify and describe properties of visible light (e.g., prism to demonstrate
spectrum of colour)
o Show how light is transmitted and absorbed by different materials (e.g., opaque,
translucent, transparent; creation of shadows)
o Demonstrate how visible light is refracted (e.g., bending of rays, changes of
speed, diverging and converging lenses)
Processes of Science
 A2 perform experiments using the scientific method
Math 7:
Data Analysis:
 D1, Demonstrate an understanding of central tendency and range by determining the measures
of central tendency (mean, median, mode) and range determining the most appropriate
measures of central tendency to report findings
 D2, Determine the effect on the mean, median, and mode when an outlier is included in a data
set
Supplemental table for volunteer to write on board (volunteer may have to write more rows)
Table 1. Class data for balloon popping experiment: time for single
Balloon Color (ROYGBIV)
Time to pop (seconds)