# Drop Device Inquiry: Investigating Liquids

Sandi Graham and Jim Keighton
Museum of Life and Science
Durham, NC
1994 ASTC Annual Conference
Seattle, WA

This is a write-up of the design of a 3 hour staff development workshop on inquiry using liquids as a vehicle. This workshop was done with all the elementary teachers from Durham, North Carolina during the summer of 1994. Below is a brief description of the workshop, a template for the design of this workshop that can be used for other inquiry topics, and a list of questions that teachers asked after observing a drop device.

This workshop began with teachers observing a drop device (a cheap plastic novelty that has two or more colored liquids in it. When the device is turned over, one of the liquids forms round drops that sink through the other liquid, sometimes flowing down ramps, turning wheels etc). After observing for a short time, the teachers shared all the questions they had raised based on their observations. Then, the teachers were given a variety of household fluids like water, salad oil, rubbing alcohol (see list of materials below), and asked to use the materials to try to answer their questions. After their investigations, they discussed the experience and what they might do next if they had more time.

Introduction
The following outline is one way of considering and planning an inquiry-based science experience in the classroom. It describes the process of organizing the initial exploration with materials; discussing, summarizing, and clarifying questions for continued investigation; and developing further explorations and applications.

Considering the possibilities for children's learning in an activity can facilitate the progression from observation to investigation. Thinking through objectives can help you construct situations that stimulate students to ask questions and to undertake activities which help provide answers. Development of a concept is not achieved through a single activity but as a result of prolonged exploration and a wide variety of problem solving opportunities.

Below are 8 questions to ask to help design a particular inquiry topic. They are answered below for the topic of fluids.

```1.  What are my objectives?
A. What are the "big ideas"?
1. Properties of matter
Matter exists in solid, liquid, and gaseous forms.
Liquids have certain characteristic properties: density, viscosity, surface tension, miscibility
2. Introducing an inquiry method for doing science
B.  What content area do I want students to investigate?
Properties of matter through a study of liquids

A. Pre-assessment strategies
What do students know about liquids?
What questions do they have about liquids?
Record what they say in some systematic fashion
Use familiar material to focus attention: salad dressing
B. Informal assessment
Use students initial investigation with materials to assess prior knowledge

III. How will I introduce this topic?
A. Observation of a drop device
1. How can I help students make observations?
What do you notice happening?
Tell me what you see...
Did you notice that...?
What questions do you have about?
2. What questions might students raise?
The liquids in the cylinder
Drop rate/ speed of drops
Construction of the cylinder
Drop behavior
The way things look through the cylinder
Role of air in the cylinder
B. Processing
How can I help students share their observations and questions?
What did you notice?
What did you find out?
Do other people have the same questions?
What questions about liquids do you have now?

IV. What materials will best lend themselves to an investigation of this
topic?
A.  Are there everyday materials with which to begin an exploration?
Salad oil, mineral oil, water, salt water, clear detergent or shampoo, white vinegar,
rubbing alcohol, Karo syrup, glycerin, food coloring
B.  What additional materials will we need to facilitate our exploration?
Eye droppers, dropper bottles, test tubes or other clear containers, stoppers or corks,
stopwatches, waxed paper, newspaper, toothpicks, basins or buckets, paper towels,
paper, markers, pencils, test tube holders
C.  How do I make allowances for students' need to "mess about" with liquids  as an
essential part  of  the initial exploration?
Know that all students come to the exploration with different
experiences with liquids
Know that familiarity with the substances is an essential
Provide ample opportunity for students to explore the liquids
without a formal question to investigate

V.  What concepts might arise through an investigation with these materials?
Some liquids are heavier than others (density).
Some liquids do not mix together (miscibility).
Some liquids are thicker than others (viscosity).
Some liquids stick together more than others (surface tension).

VI. How might we investigate these concepts in a systematic way?
A. Identifying and formulating investigatable questions
1. What questions do you have about liquids?
Which liquids are heavier than other liquids?
Which liquids mix together and which do not?
Which liquids stick together to form bubbles?
Does one kind of liquid form bubbles in all the other liquids?
2. Which of these questions can we begin to find answers to?
3. Can we restate other questions in ways that make it easier to look for
B. Planning systematic investigations
Which question will you try to answer?
What procedure will you use?
What equipment and materials will you need?
How will you record your observations?

VII. How will the results of these investigations be processed?
A. Sharing in teams
Formulate a summary of results
Identifying other questions which were raised
B. Sharing in the whole group
Communicate and discuss results based on observations
Compare and interpret data
Generate further questions
Plan further investigations

VIII. How can we begin to apply the concepts in other ways?
A. What are some applications of density?
How can you make something that sinks float?
Why is it easier to float in ocean water than in fresh water?
B. What are some applications of miscibility?
Why do some salad dressings stay mixed and others do not?
Why do bottles of food, medicine direct to "shake well before using"?
C. What are some applications of surface tension?
How can water striders and other insects walk upon the water?
Which shapes of boats float upon the water?
D.  Do all liquids distort the image of an object in the same way?
E.  How do balls or bubbles behave on ramps of different shapes?
F.  Is It possible to create a device with liquids or other fluids that keeps time? ```

DROP DEVICE QUESTIONS
Why does the drop hug the side? Is it the shape of the ramp or the G force?
Why do some drops travel faster?
Why do the drops bounce?
What purpose does the center piece serve?
Why do the drops stay as distinct drops?
Why do bubbles come out at regular intervals?
What would happen if you shook the device?
What are the two liquids?
Do the air bubbles affect the bubbles coming down?
Is the liquid going in or just joining and taking up less space?
How did they get this thing together?
What would happen if we did it with other materials?
How will we know when it will stop?
If you left it long enough, would we just have a sea?
Do the dots change size as they progress?
Is it an optical illusion that the drops are triangular at the bottom?
How long does it take?
Are there always the same number of drops?
Should we wait until it stops to turn it over?
Is the interval between drops getting longer?
Where does it go back in?
How does touching (heat temperature) change it?
Will it make drops if you turn it upside down without shaking?
Why don't the liquids mix?
How long does it take for a drop to go from top to bottom?
What happens in the middle --- does the middle bubble change?
Why does the surface of the blue look silver when it is placed on its side?
Which liquids take the food coloring?
Does the liquid that takes the color need to be heavier than the medium?
Which different liquids can we use to dilute the coloring so that the bubbles will sink?
Is oil the only liquid that the dye is not soluble in?
What happens to different liquids when dropped in oil?
Why are some bubbles bigger than others?
What determines the speed of the drip?
Why does the blue stuff go down instead of float?
Why do the little blobs eventually make a big glob?
Are the balls rolling or sliding?
Why does the air go up?
Does there have to be air in there?
How are the bubbles able to bounce off each other instead of globbing together?
Why do the bubbles flatten momentarily when they fall off the ledge?
Why do bubbles slow down when they get to the edge of the ramp?
Why are the colored bubbles so big at the start?
Why don't the bubbles all join on the way down?
How long does it take for the flow to regulate itself?

Reprinted with permission of the authors.