Observations & Interpretations: Engaging Students in Classroom Experiments

The student participation form may be introduced at the beginning of the chemistry unit for Physical Science 9 or a Chemistry I course. A demonstration using a potato candle as a discrepant event is well adapted to the participation form and adds a humorous twist that reinforces the importance of careful scientific investigations.

Observations & Interpretations: Engaging Students in Classroom Experiments and< Discrepant Event Demonstrations
Sherri Seifert
Sleepy Eye Public High School
Sleepy Eye, MN 56085

Reference: Potato Candle; Wayne Haag, Century College, White Bear Lake, MN


This is an interesting, engaging method to emphasize and clarify for students the importance of differentiating between observations and interpretations, and qualitative and quantitative observations. Students will also realize how a hypothesis may change as new experimentation is applied to an initial work.

The student participation form provides a metacognitive guide as the experiment is attempted or demonstrations is viewed. The topic or title is noted on the top of the form by students and their observations/hypothesis completed during and after the activity. This format is meant to keep students responsibly engaged in the topic and reinforce the MN Science Standards for grades
9—12.
History & Nature of Science Scientific World View Benchmarks #3,5
History & Nature of Science Scientific Inquiry Benchmarks #1,2

The student participation form may be introduced at the beginning of the chemistry unit for Physical Science 9 or a Chemistry I course. A demonstration using a potato candle as a discrepant event is well adapted to the participation form and adds a humorous twist that reinforces the importance of careful scientific investigations.

A copy of the student participation form and the potato candle discrepant event demonstration follow.


Name: __________________________
Course: _________________________

Class Experiment / Demonstration

Topic: _____________________________
Observations: (Note at right if qualitative (ql), quantitative (qt), or interpretation(I)

__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______
__________________________________________________________________ ______

Hypothesis:

1. _____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________

2. _____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________



Discrepant Event: Potato Candle

Materials: Equipment:
1 potato matches
1 Brazil nut cut into slivers for wicks 8 cm square cardboard
lemon juice tack
core borer
Set up: Using the core borer or trimming by hand, shape a potato into a candle-like object. Carefully trim the Brazil nut into slivers to act as a wick, sticking it into the end of the potato candle. Push a tack up from the center-bottom of the cardboard square and fit the potato candle onto it for stability.

Procedures:

1. (Re)introduce topics of qualitative and quantitative observations and their importance in scientific experimentation. Discuss the differences between observations and interpretations.
2. Pass out Student Participation Forms for classroom experiments and demonstrations.
3. With the demonstration set up, ask students to write down as many observations they can about the object. Never use the word "candle." Always refer to the "object." Have them number each observation on the form.
4. Light the object and have students continue to make observations. After a couple of minutes, blow out the flame.
5. Have students read through their observations and write a testable hypothesis that attempts to explain their observations (hopefully they will conclude the object is a candle).
6. Discuss how a hypothesis may change on the basis of further experimentation. Inform students you will perform a final step in the demonstration.
7. Take a bite out of the object and eat it! Ask if they would like to change their hypothesis based on the results of the final step. Write the new hypothesis as #2. What is the identify of the object?

Discussion:

• Ask students to share observations.
• On their participation forms, ask students to note at the right side if their comments were qualitative and quantitative observations or were they interpretations?
• Discuss the importance of careful and thorough observations in future activities using qualitative and quantitative information. Note also that many hypotheses have needed to be altered as scientists of the past and present continue to challenge scientific ideas with additional experimentation.

See activity description

I will collect student participation forms for review and points. Applying this to a lab practicum may work as a form of assessment.

Grades 9 - 12
History & Nature of Science Scientific World View Benchmarks #3,5
History & Nature of Science Scientific Inquiry Benchmarks #1,2