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Soapy Water
Administration Procedures
Contributed by: Connecticut Academic Performance Test (CAPT)


The CAPT Science Framework was developed by an advisory committee of Connecticut educators and is based on current research and theory about science instruction and assessment. The CAPT Science Framework is based on the idea that science is not only a body of knowledge, but also a way of thinking about the world around us and a concern how that knowledge is used. The framework thus addresses three major questions: What do students know in science? (Conceptual Understanding), What do students do with their scientific knowledge? (Application), and How do students know in science? (Experimentation). The content is drawn from three major areas (Life Science, Physical Science, and Earth/Space Science). The CAPT Science Framework was developed using the Connecticut Guide to Curriculum Development in science, as well as various national efforts in science education including Project 2061's Science for All Americans, the National Science Teachers Association's Scope, Sequence and Coordination's Content Core and the emerging National Science Education Standards. It should be noted that the science component of the CAPT is not a test of high school science content, but rather a cumulative assessment covering science content and skills that students should have acquired in grades K-10.

Assessing Experimentation

Science is not a matter of belief; rather, it is a matter of conclusive evidence that can be subjected to the tests of observation and objective reasoning. Experimentation and the ability to apply scientific reasoning to solve problems is a major focus of the science assessment.

To assess experimentation, students participate in a hands-on laboratory activity several weeks prior to the written test. This performance task asks students to design and carry out their own experiment to solve a problem and write about their results in an authentic format. Students are not scored on their actual performance on this task at the state level. Rather, teachers are encouraged to score their own students' work and provide students with feedback about their performance. On the written test, students are given follow-up questions which relate directly to the hands-on task. These questions are scored at the state level and become part of the student's score on the science portion of the CAPT.

CAPT Science Processes

  1. Conceptual Understanding and Application
    • Description - use of scientific knowledge to provide accurate names for natural phenomena and for purposes of classification
    • Explanation - use of scientific knowledge to explain natural phenomena
    • Prediction - use of scientific knowledge to generate predictions about future events
    • Application - use of scientific reasoning and knoweldge to solve daily life problems and technological problems, recognizing its potential and limitations
    • Communication - use of scientific words, graphs, charts and equations to explain scientific phenomena

  2. Experimentation
    • Define the problem
    • Formulate a hypothesis
    • Test the hypothesis: design and conduct appropriate experiments
    • Make, record, and interpret observations
    • Draw conclusions and discuss their validity

CAPT Science Content Areas

  1. Life Science
    • Characteristics of living things
    • Cells, genetics, and evolution
    • Ecosystems
    • Human biology
    • Issues in bioethics

  2. Physical Science
    • Structure of matter
    • Reactions and interactions
    • Force and motion
    • Energy sources and transformation
    • Heat and temperature
    • Magnetism and electricity
    • Sound and light

  3. Earth/Space Science
    • Astronomy
    • Geology and natural resources
    • Oceanography
    • Meteorology
    • Earth history and dynamics

National Science Education Standards:

12 A SI 1: Science as Inquiry: Grades 9-12

1.4 Formulate and revise scientific explanations and models using logic and evidence. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.

4 B PS 1: Properties of objects and materials: Grades 5-8

1.2 Objects are made of one or more materials, such as paper, wood and metal. Objects can be described by the properties of the materials from which they are made, and those properties can be used to separate or sort a group of objects or materials.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National Council of Teachers of Mathematics:

DAP1: Formulate questions that can be addressed with data and collect, organize, and display relevant data to answer them:
Grades 9-12 j. understand the differences among various kinds of studies and which types of inferences can legitimately be drawn from each
Grades 9-12 k. know the characteristics of well-designed studies, including the role of randomization in surveys and experiments

DAP3: Develop and evaluate inferences and predictions that are based on data :
Grades 9-12 h. evaluate published reports that are based on data by examining the design of the study, the appropriateness of the data analysis, and the validity of conclusions

PS2: Solve problems that arise in mathematics and in other contexts:
Grades 9-12

COM1: Organize and consolidate their mathematical thinking through communication:
Grades 9-12

CAPT Science Performance Task: Soapy Water
Grade 10

Local water treatment plants often remove environmentally harmful impurities, such as soap, from waste water before returning it to the environment.

One way to remove soap from water is to have it react with other substances. When these reactions occur, a solid called a precipitate is sometimes formed. The precipitate can be filtered out of the water.

Student's Task:
The students will design and conduct an experiment to explore the use of several substances in removing soap from water. During this activity they will work with a lab partner (or possibly two partners). The students must keep their own individual lab notes because after they finish, they will work independently to write a lab report about the experiment.

The materials listed below should be provided for each lab group. It may not be necessary for the students to use all of the equipment that is provided. You may use additional materials or equipment if they are available.

Powdered soap
Table salt
Epsom salt
4 paper cups
8 clear plastic cups
4 white plastic spoons/stirring rods
Graduated cylinder
Access to tap water
Access to a balance
Access to a clock or watch with a second hand
Paper towels for cleanup
Splash-proof goggles and apron for each student
4 test tubes
Test tube rack
Test tube brush
Parafilm (to cover test tubes)
Marking pencil
5 paper cones
5 pieces of filter paper
1 beaker
Labeling dots


Item 1
This item assess students' understanding of conclusions drawn from scientific investigations and factors that affect their validity. The results of the experiment seem to indicate that soap has been removed form the water by the Epsom salt; however, this conclusion should be questioned. The color of the filtrate and presence of a precipitate do not mean that all of the soap has been removed. The group did not include a control in their experiment for comparison purposes. The groups also could have performed a shake test on the filtrate to see if suds formed, indicating the presence of soap. It is also unclear if important variables that affect the validity of the conclusion have been controlled in the experiment.
CAPT Framework
Experimentation: Draw valid conclusions and discuss their validity.

Item 2
This item assess students' understanding of what constitutes a complete experimental design. In this case, students do not have all of the information they need to replicate the experiment. Students are given some information, such as the substances added to the soapy water, and general procedures that were followed. However, other important information, such as the amount of soap added to the water, the amount of soapy water added to each cup, and the amount of each substance added to the cups, is needed.
CAPT Framework
Experimentation: Design and conduct appropriate experiments.

Item 3
This item assess students' understanding of what makes an appropriate control in an experiment. In Group B's experiment, an appropriate control would have been a cup containing 50 mL of soapy water in which nothing was added. The control should have been filtered and the filtrate shaken, just as with the other samples. The control would improve the experiment because it would serve as a basis of comparison to determine if any of the substances removed soap from the water. The control would show if filtering alone removes soap.
CAPT Framework
Experimentation: Design and conduct appropriate experiments.

Item 4
This item assess students' understanding of what constitutes an appropriate experimental design. Group B's experiment is somewhat better although each experiment has its flaws. Group B specifies the amount of each material used (soapy water, salts, sugar) and uses a shake test as a quantitative measure of soap left in the water. Neither group included a control in their experiment, neither performed multiple trials, and it is not clear if all variables have been controlled in either experiment.
CAPT Framework
Experimentation: Design and conduct appropriate experiments.


  • Be careful.
  • Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.


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