Dancing Raisins

Teacher Directed Mini Learning Cycle

(Teacher)

This activity is a complete learning cycle designed for the first week of school[1]. All three stages of the learning cycle: Exploratory, Concept Development and Application are explained as the students utilize the science process skills of observation, classification, inference, hypothesizing and formulating models.

Problem: What affect do assorted liquids have on the behavior of raisins placed in them?

Materials: raisins, assorted clear liquids such as water, 7 –Up™, Mountain Dew™, baby oil, corn syrup, clear glass containers (plastic containers do not work as well).

Procedure:

  1. Provide each group of students with a snack box of raisins, and several clear glass containers. After the initial discussion as outlined in #2 of this section, students are told to experiment on their own and record what they see.
  1. Teacher should preface the activity with a statement similar to the following:

Scientists design and perform experiments in order to analyze the world around them. They manipulate variables, make and record observations, develop a rule or law that explains their observations, and determine where in the “real world” this rule applies. The goal for this class is to undertake a similar activity. Given the equipment, they can experiment with the materials by altering the variables and develop a generalized statement or rule that explains the observations. Finally they will attempt to determine where the identified behavior is found in every day life - either in nature or through man made inventions.

Students may need to refer to a list of science process skills prior to beginning the investigation.

The preliminary experimentation and the resulting observations of the students are the Exploratory phase of the learning cycle as utilized in this experiment.

Exploratory phase of learning cycle:

Examples of student procedures:

·  Students will drop raisins into assorted liquids and record whether bubbles of CO2 collect on the raisins.

·  Some students may smooth out their raisins or peel them prior to dropping them into the liquids.

·  Others will just dump the entire box of raisins into the liquid. Variable control is a concept that is not clearly understood.

·  Prompt students to record what they change as they proceed with their experiment.

Examples of Sample Observations:

·  Raisins placed in carbonated beverages collect bubbles, rise to the top, lose the bubbles and sink again.

·  Raisins prefer to dance near the edge of the cup.

·  Bubbles get larger as they rise and then pop at the surface of the carbonated beverage.

·  Non-carbonated beverages do not have this effect.

·  Clumps of raisins are too massive and do not “dance”. Smaller single raisins dance best.

·  The more wrinkled the raisin the better it dances.

·  Flattened raisins or raisins without their skin do not dance well.

·  The colder the pop, the more bubbles, and the faster the raisins dance.

·  Stirring the liquid makes the bubbles disappear and raisins take longer to rise to the top and dance.

·  Raisins left in the liquid bloat and stop dancing.

Concept Development phase of learning cycle:

When all students have their observations recorded, have them list the observations and begin the Concept Development Phase of the learning cycle through the development of a sample rule. Have students group similar observations together until a conclusion can be drawn as to the significance of each observation.

Sample Rule: The bubbles from the soda collect on wrinkled surfaces and buoy up the raisin because the raisin becomes lighter than water and floats. At the surface the bubble pops and the raisins are heavier than water and sink.

At this point the instructor fine-tunes the rule to include information regarding buoyancy and density of objects that float. The instructor may also prompt students to investigate such variables as raisin size, wrinkles etc if those variables weren’t investigated by students within the class.

Application Phase of learning cycle:

Finally the instructor makes a compilation of suggestions from students as to where they might see applications of the observed phenomena in the “real world”. Examples include fish bladders, ballasts on submarines, scuba diving vests, and weather balloons.

All three stages of the learning cycle have been utilized and explained to the students in an interesting manner. The hook has been set, students are more comfortable with their decision to take physics and believe that the class will be fun and applications of the concepts will be made to their everyday world.

Jan Mader and Mary Winn

[1] Two articles on teaching using learning cycles are included in the section of this book titled “Teacher Background Information”.