Controlled Experimentation with Bubbles

Arts & Letters, Brooklyn

Summer Research Program for Science Teachers

August 2012

Subject: Controlled Experimentation/”Scientific Method”

Unit: Thinking Like a Scientist

Time required: 50 minutes

Note: This lesson can be a good introduction to controlled experimentation or it can be used later in the unit. You can tweak this lessen depending on this i.e. If you are going to do this later, you may want to have students identify the constants, IV and DV before the lesson.

New York State Standards:

S2.1d use appropriate tools and conventional techniques to solve problems about the natural world, including:

• measuring
• observing
• describing
• classifying
• sequencing

S2.2d identify independent variables (manipulated), dependent variables (responding), and constants in a simple controlled experiment

S2.3b conduct a scientific investigation

Materials:

Various different brand names of bubbles (can be purchased at 99 cent store)

Paper towels

Rulers/measuring tape

Notebook for recording data

Question: Which brand of bubbles makes the biggest bubbles?

Procedure:

1. Pair up with your partner and choose one brand of bubbles (up front)

2. Open the bottle and record your initial observations in the chart (see board)

3. Remove the stick and blow a bubble onto the surface of your table.

4. Allow the bubble to pop or gently pop it your self.

5. Record the diameter in your chart.

6. Calculate the average and record this average on the class data chart on the boar

Initial Observations of Bubble Liquid

 Brand of Bubbles Initial Observations (see, smell, feel etc.)

Diameter of Bubble

 Trial Diameter of Bubble 1 2 3

Average ____________ (include units!)

Conclusions:

1. What are the independent and dependent variables?
2. What are the variables that you should have kept constant to minimize error?
3. Based on the class data, which brand of bubbles produced the biggest bubbles? Use the data to back up your statement!
4. What do you think could have caused the differences in diameter of the bubbles produced by different brands?

If you teach Living environment, these questions can also be given to assess understanding:

Conclusions based on an experiment are most
likely to be accepted when:

(1) they are consistent with experimental data and observations
(2) they are derived from investigations having many experimental variables
(3) scientists agree that only one hypothesis has been tested
(4) hypotheses are based on one experimental design

Which statement about the use of independent variables in controlled experiments is correct?

(1) A different independent variable must be used each time an experiment is repeated.
(2) The independent variables must involve time.
(3) Only one independent variable is used for each experiment.
(4) The independent variables state the problem being tested.

A scientist conducted an experiment to test the hypothesis that maple seeds exposed to acid rain will take longer to germinate than
seeds exposed to normal rain, which has a pH of 5.6. The scientist set up four groups, each containing 200 maple seeds. The water used for
each group had a different pH value: 5.6, 4.0, 3.0, and 2.0. All other conditions were kept the same. After ten days, the number of seeds that
had germinated in each group was counted.

73 Identify the dependent variable in this experiment. [1]