Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. Using a hot plate, heat 1.5 L of distilled water in a 2000-mL beaker to 45 °C. Note: Water from a hot water tap may be used as an alternative to heating the water on a hot plate. If additional hot plates are available, multiple smaller beakers may be used.
2. Fill three remaining 2000-mL beakers with 1.5 L of distilled water each.
3. In one beaker, add the entire contents of 1 M hydrochloric acid (15 mL). Stir the solution and label the beaker acidic water.
4. In a second beaker, add the entire contents of 0.1 M sodium hydroxide. Stir the solution and label the beaker basic water.
5. Using hot plates, heat the three beakers (steps 2–4) of liquid to 30 °C. Note: Water from a hot water tap may be used as an alternative to heating the water on a hot plate.

Safety Precautions

Hydrochloric acid solution is highly toxic by ingestion and inhalation and severely corrosive to skin and eyes. Sodium hydroxide solution is also very corrosive to skin and eyes. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Combine the hydrochloric acid and sodium hydroxide solutions to neutralize and the resulting solution may be disposed of according to Flinn Suggested Disposal Method #26b, down the drain. The sponge creatures may be disposed of according to Flinn Suggested Disposal Method #26a or they may be rinsed in clean water and saved.

Lab Hints

• Enough materials are provided in this kit for 30 students working in pairs or for 15 groups of students. Both parts of this laboratory activity can reasonably be completed in one 50-minute class period.
• Hot tap water may be used as an alternative to heating water on a hot plate. Adjust the water to yield 30 °C and 45 °C temperatures.
• The capsules will not dissolve in water cooler than 30 °C.
• Allow students to decide when the creature is fully “developed.” The creatures are all different shapes which unfold after the outer capsule dissolves.
• Since the sponge creatures are manufactured as a toy item, the composition of the capsule may change without notice. The lab is designed as a hypothesis and test. It is possible that trend of acid–neutral–base time results may vary from those specified in the sample data. However, the lab will still serve as an effective means of teaching the scientific method.

Teacher Tips

• Affix magnets to the back of the sponge creatures after they dry and place them on magnetic white boards or file cabinets.
• Use the sponge creatures to teach about symmetry.

Sample Data

Part 1

Problem
Does temperature affect the development rate of sponge creatures?

Hypothesis

As water temperature increases the rate of development of the sponge creatures increases because many processes in nature are accelerated with increased temperature.

Student data will vary. Observations may include the color, shape or texture of the sponge creature or capsule. They may also include observations about the rate of expansion or the process of expansion. Accept all appropriate observations.

The hypothesis was supported since the water with the higher temperature allowed the sponge creature to develop five times faster.

As pH decreases or increases, the rate of development of the sponge creature will increase because anything other than neutral is more corrosive so it will break down the capsule faster.

Observations may include the color, shape, or texture of the sponge creature or capsule. They may also include observations about the rate of expansion or the process of expansion. Accept all appropriate observations.

Based on the results above, the hypothesis was not supported because the water with a pH of 10 produced a slower rate of development for the sponge creature than the water with a pH of 4.

Answers to Questions

1. Did the 30 °C water or the 45 °C water produce the fastest development time for the sponge creatures?

   The sponge creatures developed faster in the 45 °C water.

2. What is the relationship between temperature and the rate at which the sponge creature develops?

   The rate of development increases with the temperature of the water.

3. Based on the results from the effect of temperature on the sponge creature’s development rate, predict how boiling water would affect the development of the sponge creature? Ice water?

   Boiling water should dramatically increase the rate of development of the sponge creatures. Ice water should retard the rate of development, if it allows the capsules to expand at all.

4. Did a pH of 4 or a pH of 10 produce the fastest development time for the sponge creatures?

   pH 4 produced the fastest development for the sponge creatures.<?p>

5. What was the relationship between pH and the rate at which the sponge creature develops?

   As pH decreases (becomes more acidic) the rate of development of the sponge creatures increases.

6. Besides temperature and pH, what other factors might affect the rate of development for the sponge creatures?

   Student answers will vary. Accept all plausible answers.

7. Design an experiment to test one of the other factors listed above.

   Student designs will vary. Accept all appropriate and safe designs.

Introduction

Science is the field of study that aims to provide explanations and answers to the many questions we have about our world. Scientific investigations are essential in understanding science. The scientific method is a set of steps used by scientists to answer questions about puzzling phenomena, and it also allows scientists to systematically investigate the natural world in search of explanations.

Concepts

• Scientific method
• Experimental design
• Interpreting data
• Drawing conclusions

Background

The scientific method is a way of solving problems using a systematic approach. When you observe the world around you, conclusions are drawn based on your observations. To answer a question, a hypothesis is formulated. A hypothesis is a possible answer or explanation to a problem or question. Based on a series of observations, the hypothesis is tested by means of experiments designed to either support or invalidate the hypothesis. Scientific knowledge is continually changing and becoming more reliable as we gather more information and test hypotheses.

The scientific method is sometimes presented as a rigid sequence of events. The scientific method, however, is not rigid, it is a process—a process of discovery! Discovery begins when we make observations and then try to understand what we have observed by asking key questions and proposing possible answers. The process of discovery continues as we design and conduct experiments to test whether our answers to these questions are valid.

The following is a list of “typical” steps that scientists may use to solve a problem. Keep in mind, however, that the strategy and the order of steps may vary greatly from problem to problem.

Typical Steps in the Scientific Method

• Define a problem or ask a question—A clear statement of the problem or question is a crucial step in beginning an investigation.
• Make observations about the problem—All possible information on the problem will be helpful in writing a plausible hypothesis and in designing a good experiment.
• Develop a hypothesis—This is a possible answer or tentative explanation of the problem or question. It should be based on facts and observations and should be capable of being tested.
• Design and implement an experiment—Experimental testing will provide evidence which either supports or contradicts the hypothesis. Only one variable is tested at a time and it is the only one that will produce the observed results. All other factors must be held constant.
• Record and analyze data—Data, such as observations and measurements, are recorded and then analyzed. If the data support the hypothesis, then the conclusion would state that the hypothesis is correct. If the data contradict the hypothesis, then a new hypothesis must be made and tested.
• Draw a conclusion—Scientists base their conclusions on observations made during experimentation. When a hypothesis has been tested many times and has proven to be correct, it becomes a theory. However, a theory is still not a law.

Experiment Overview

Discover the effect of both temperature and pH on the rate of development of sponge creatures. Does the rate of development increase or decrease with an increase in temperature? Does the rate of development increase or decrease with an increase in pH?

Materials

Safety Precautions

The acidic and basic water solutions are made using hydrochloric acid and sodium hydroxide. Hydrochloric acid solution is highly toxic by ingestion and inhalation and severely corrosive to skin and eyes. Sodium hydroxide solution is also very corrosive to skin and eyes. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

Part 1

1. Develop a hypothesis to answer the question, “does temperature affect the development rate of sponge creatures?”
2. Record the hypothesis on the How Scientists Do Science Worksheet.
3. Using a marker, label one cup “30 °C” and label another cup “45 °C.”
4. In the cup labeled “30 °C,” pour approximately 100 mL of the 30 °C water. Use a clean graduated cylinder. Place a thermometer in the water and measure that the water temperature is 30 °C. If not, record the actual temperature.
5. Place one sponge creature into the cup and stir using a plastic stirrer.
6. Using a stopwatch or clock with a second hand, observe the amount of time required for the sponge creature to completely expand to its final form.
7. Record the time required for the sponge creature to completely expand, as well as any other observations, on the How Scientists Do Science Worksheet.
8. In the cup labeled “45 °C,” pour approximately 100 mL of the 45 °C water. Use a clean graduated cylinder. Place a thermometer in the water and measure that the water temperature is 45 °C. If not, record the actual temperature.
9. Place one sponge creature into the cup and stir using a plastic stirrer.
10. Using a stopwatch or clock with a second hand, observe the amount of time required for the sponge creature to completely expand to its final form.
11. Record the time required for the sponge creature to completely expand, as well as any other observations, on the How Scientists Do Science Worksheet.
12. On the How Scientists Do Science Worksheet, write a conclusion statement including whether the hypothesis was supported or not.

1. Develop a hypothesis to answer the question, “does pH affect the development rate of sponge creatures?”
2. Record the hypothesis on the How Scientists Do Science Worksheet.
3. Obtain two clean cups.
4. Using a marker, label one of the clean cups “Acidic” and the other “Basic.”
5. In the cup labeled “Acidic,” pour approximately 100 mL of the acidified water. Use a clean graduated cylinder.
6. Using one of the pH strips, test the solution and record the pH.
7. Place one sponge creature into the cup and stir with a plastic stirrer.
8. Using a stopwatch or clock with a second hand, observe the amount of time required for the sponge creature to completely expand to its final form.
9. Record the time required for the sponge creature to completely expand, as well as any other observations, on the How Scientists Do Science Worksheet.
10. In the cup labeled “Basic,” pour approximately 100 mL of the basic water. Use a clean graduated cylinder.
11. Using one of the pH strips, test the solution and record the pH.
12. Place one sponge creature into the cup and stir with a stirrer.
13. Using a stopwatch or clock with a second hand, observe the amount of time required for the sponge creature to completely expand to its final form.
14. Record the time required for the sponge creature to completely expand, as well as any other observations, on the How Scientists Do Science Worksheet.
15. On the How Scientists Do Science Worksheet, write a conclusion including whether the hypothesis was supported or not.
16. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

13547_Student.pdf