Scientific Investigation

Part I: Evaluate one experimental design. (10 points)

Part II: Design your own experiment using the scientific method. (40 points) Review each scenario below, and choose one to complete for your assignment. Each scenario contains specific questions that will ask you to provide examples, explain your suggestions for improvement, and refer to the lesson. Be sure to respond to each question in complete sentences. Part I: Scenarios (select only one)

Scenario 1

Christopher and Kate noticed that after a rainstorm some of the rocks in their yard appear to shrink.

They wondered how the mass of the rocks changed when dissolved in water. To determine this, Kate purchased a variety of rocks from a local shop, carefully recording the types of rocks in a data chart. Christopher gathered rocks from the backyard to add to the rocks Kate purchased. They measured each rock’s initial mass; then they inserted the rocks one by one into 100 milliliters of water and measured the mass of each rock after it had sat in the water for five minutes.

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Both Christopher and Kate concluded that store-bought rocks do not dissolve in water. They also concluded that to get rocks that dissolve in water they must be gathered directly from the yard.

1. Describe why the investigation above is not adequate to explain what types of rocks will dissolve in water.

2. Using what Christopher and Kate have already observed, suggest a possible hypothesis regarding how the mass of a rock changes when placed in water. Identify the independent and dependent variables.

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3. Describe, in detail, a procedure to test your hypothesis. Identify the controlled variables.

Scenario 2

Lizzie loves to stargaze at night. She has noticed that the moon appears to change shape over the course of the month, and she wants to investigate why this happens. She hypothesizes that the relationship of the sun, Earth, and moon creates shadows on the moon. She sets up an experiment with a light bulb to represent the sun, a large beach ball to represent Earth, and a smaller foam ball to represent the moon. She researches the position of the sun, Earth, and moon at different times of a month and makes a model of the entire system.

1. Identify the parts of the scientific method in Lizzie’s experiment.

2. List at least three variables Lizzie should control during the experiment. For each variable identified, give a specific suggestion for how Lizzie can control it.

Scenario 3

Matthew notices that if he walks barefoot on blacktop pavement, his feet get much hotter than if he walks barefoot on grass or dirt. He wants to determine if the amount of blacktop pavement in a city will affect the overall temperature of the city. His hypothesis states that because the pavement absorbs heat from the sun, a city with more pavement will have a higher temperature. Matthew uses a map to measure the number of miles of pavement within the limits of his hometown. He then records the temperature outside of his house to see how it varies each day for one week. He asks his friend in the next town to complete a similar experiment.

Once the data is collected, he concludes that the hypothesis is not supported.

1. What are the major flaws in Matthew’s experimental design? What are the strengths of the experimental design? Explain each in detail using terms from the lesson.

2. This experiment is not able to support Matthew’s hypothesis. Suggest specific improvements that will allow the experiment to more effectively test the given hypothesis. Explain why these changes are improvements.

Part II: Designing an Experiment (select only one)

For the second part of your assignment, you will apply the scientific method to a real-life situation. You will select a problem that leads to a testable question, similar to the scenarios presented in Part I and explain how you would follow each step of the scientific method to try and answer the question or solve the problem. Note: you are describing only what you would do at each step; you will not be conducting the experiment. Choose one of the following four problems to design your experiment.

Problem 1

Your family has planted a garden. You observe that some of the plants in the garden have teeth marks in them. What is eating the plants?

Problem 2

A local farmer notices that the level of water in the pond behind his house has been going down. Temperatures have been very high in the area, but there are also a lot of animals on his farm that may be drinking the water. What is causing the water to go down?

Problem 3

The crowds at the local beach have decreased over the last week. Temperatures are very high in the area, but people seem to be staying away from the beach. Why?

Problem 4

As you are walking down a wooded path, you notice a large depression in the ground that has burn marks along the outside. What caused the hole?

Part II: The Process

View this table to see what you will need to include in your experimental design.

Experimental Design Process Parts of the Scientific Method What You Need to Do Example Purpose This step should include a description of the scenario you are investigating, along with the question that you are attempting to answer. It is important that each question/problem has a variety of possible solutions to investigate, thereby allowing you to use the scientific method. Scenario: My car won’t start. My question is: “Why won’t my car start?”


List all the possible observations that you can make about the question/problem stated in the purpose of the experiment. I noticed that the engine made a clanging sound when it started.

The car is 15 years old.

It has been more than two weeks since I last bought gasoline.


Explain what specific topics you would research to attempt to solve this problem, and describe at least two practical resources you would use for your research. I look through my car’s manual for reasons why the car might not start. I also call my friends to see if they have ever had this problem with their cars.


List at least two possible hypotheses that could apply to your question above. Choose one hypothesis, or “educated guess,” that you will test with an experiment. Two possible hypotheses are “If I put fresh gas in my car, it will start” and “If I get a friend to jump my car’s battery, the car will start.” I decided to choose “If I get a friend to jump my car’s battery, the car will start.”


Describe an experiment to test your hypothesis. Be sure to identify the independent and dependent variables, as well as all the controlled variables. Make sure that the experiment’s procedure provides instructions for controlling the controlled variables and that it will test the hypothesis you are proposing. 1. Read the car manual to make sure I know where to connect the jumper cables. 2. Connect jumper cables from my friend’s car to my car, making sure not to change anything else in the process (i.e., do not move any wires or belts; do not change the amount of gasoline or oil). Follow all safety directions as we attempt to jump my car’s battery each day for two days.

Independent variable: battery power

Dependent variable: car starting

Controlled variables: gasoline, oil, wire connections, and other components of the engine


Describe the data that you will collect to test your hypothesis. How will you organize your data to make sure that it is neat, verifiable, and easy to understand?

Date: Results: May 30 Car did not start; no sounds in engine; no lights. May 31 Car still did not start, but lights came on.


Describe possible results you would be looking for or measurements you would be taking, based on the experiment you designed. The car didn’t start even after we tried to charge the battery with the jumper cables.


Discuss how you would determine whether the experiment proved the hypothesis to be correct or incorrect, based on the possible results of the experiment. Then explain what you would do next if your hypothesis were incorrect. The hypothesis that I chose was incorrect because jumping the car’s battery did not get the car to start. At this point I would check my gas level and develop a new hypothesis to see if adding gas would help my car to start.

Experimental Design Parts of the Scientific Method I Chose Problem Purpose Observation Research Hypothesis Experiment Independent variables (manipulate)

Dependent variables (measure)


Analysis Conclusion

Investigative Interviewing

This refers to planning, preparation, engaging and explaining account closure and evaluation. Planning and preparation forms a critical part of an interview. This is due to the fact that interviews main objective is to determine the facts of what had already happened. Planning in the interviews context means getting ready for interview and in other hand preparation means getting all what is essential for an interview. This normally assists in smooth running of interview. All the same all interviews cannot be executed smoothly since it is impossible to prepare for all contingencies.

In planning you should establish the objective of the interview that is what you want to ascertain. Secondly, you should also know the purpose of the interview i. e. the reason you are conducting the interview. In planning it is very important to know what proof you want to cover by conducting the interview. It also important to ascertain the facts that are already established and the facts that need to be established by conducting the interview legal requirement e. g. juvenile and many other requirements should also be evaluated in the planning stage.

Finally in the planning stage you should establish what are logistical needs that are required to enhance smooth flow of the interview. This may include pens, paper, video and ERISP. The 3R’s which translate to being there at the right time, right place and right person also need to be in play. When conducting an interview, it is important to give the victim or witness enough time to reflect on and answer questions. There should also be minimum distractions. Engaging and explaining focuses on building a rapport. This is a very critical factor in all interviews as it puts the victims or witnesses at ease so that they can speak freely.

Rapport building involves introducing everybody, explaining the purpose of the interview, explaining the participants’ roles and the procedures to be followed and finally, addressing or inviting any questions. At this point of the interview, the legal requirements are fulfilled. These requirements differ a lot and the differences depend on who you are interviewing and the circumstances of the interview. Some issues to be considered include cautioning the suspect, victim or witnesses and making them aware of juat, organizing support people and obtaining an interpreter (Stacey, H. 997).

At the stage of accounting the interviewee version of what happened is obtained. It s here that the appropriate interviewing model is implemented. Cognitive interview is a suitable model of interviewing and is used when the victims are willing to give information. Its main objective is to maximize the amount of information obtained and is basically based on the principles of psychology and communication. It also allows the interviewer to tap the information stored in the interviewee’s memory.

The core skills required at the accounting stage include skills to use open questions as well as taking progressive notes as the interviewee narrates the events of the incident. This allows for a methodical approach of questioning. Moreover, this also allows the interviewer to ascertain what he/she has covered. The interviewer is supposed to use active listening skills which include the use of body language, for instance eye contact and the use of paraphrasing as a repeat of the interviewee’s responses to make sure that what the interviewee is saying is understood by both of them.

This helps to avoid ambiguity that may lead to miscommunication. The interviewer is also supposed to be skilled in the use of appropriate language (Alper, B. 1995). At the stage of closing the interview the interviewer(s) is supposed to summarize the main points, maintain an on going rapport, complete all legal requirements that include statement type-up for witness to read and sign (this is when cognitive interview is being conducted). Finally, the information acquired or gathered should be evaluated and analyzed. The evaluation should focus on the information gathered during the interview.

The evaluation should be directed to the information gathered and the interviewer’s patronage during the interview (Huff, C. et al 1996). It should be noted that poor interviewing techniques have negative ramifications for police officers that are far beyond the issues of professionalism. Principles of cognitive interview. In justice system, accurate information is critical in many ways. Whether or not a case is advanced or solved by police or even prosecuted by law, is determined to a significant extent by the information gathered from a good interview with the key witnesses or victims.

The cognitive interview was developed in the U. S by psychologists ED Heinemann and Ron Fisher. This was in response to a request from the police and legal professionals for a method of interviewing. Fisher et al discovered various basic problems in the conduct of the standard police interviews that were the root cause of ineffective and restrictive communication and interviewee performance. Cognitive interview designed by the two psychologists has over the years met the demand for an ineffective interview technique during police interviews and has evolved as a powerful instrument for gathering information from suspects or victims.

Cognitive interview focuses on handling a difficult social interaction and was initially motivated by desire to improve communication in police interviews as well as eliminating most of problems which were present in standard police interviews. Cognitive interview draws its ideas from several theories. First, it is a fact that a retrieval cue is effective to the extent that there is an overlap between the encoded data and that the retrieval cue reinstatement of the original encoding context increases the accessibility of stored information.

Also from multiple trace theory it is suggested that rather than having memories of discrete and unconnected incidents, our memory is made of association and consequently, there are several means by which a memory could be viewed (Kebbel, M and Wagstaff, G. (1996). It is true then that information not accessible with one retrieval technique may be accessible with another. The six basic principles of cognitive interviews which were developed from the above theories form the basis of cognitive interview.

They are widely used as the foundation for interaction between the interviewer and the interviewee. They include context reinstatement, extensive and varied retrieval, concentration, mental imagery, control of information exchange and finally witness with compatible questions. Context reinstatement is the first step in information retrieval and forms an integral part of a successful interview. In this stage the scene is set for the interviewee. Here, the interviewer(s) should elicit a mental reconstruction of the physical and personal contexts which existed at the time the event was experienced.

Although not always practical, revisiting the scene is always used to set the mood and to get the witness to put themselves back in time of the event by picturing it in their minds. Extensive and varied retrieval uses diverse techniques. They range from context reinstatements to different recalls. This can be done by asking the witness to draw a sketch of the scene. The interviewer can also ask the interviewee to highlight some descriptions that may be required. The more opportunities an interviewee is given to recall an event, the more the chances that he/she can accurately give the required information.

For instance, the interviewee can be asked to provide visual features of a person that is, from head to toe. In doing this, the memory is triggered and this enhances accessibility of stored information from the interviewee’s memory. The witness should form an image and an impression of the environmental aspect of the original scene, for instance, the location of objects in the room, the witnesses’ emotional reactions and feelings (surprise anger etc) as well as the physical conditions such as humidity, smoke that were present at the time of event (Kebbel, M and Wagstaff, G. 996).

A lot of concentration is a requirement whenever an interview is being conducted. Activities that can result in distractions such as noise and unnecessary movements should always be avoided and questions that are necessary and focused on the subject matter should always be asked. This will prevent psychological distractions. The interviewee should always be actively encouraged and also reminded to concentrate on the interview. To access information in the interviewee’s mind, neutral imagery is the commonly used technique.

Information is typically stored in different sensory nodes (Mine, R. and Bull R, (1999). To access this information there is need to trigger this information by questioning the interviewee to explicit recall from the relevant mental imagery. This is easily enhanced by asking the interviewee questions such as “what you could hear when you entered the room” (Mine, R. and Bull R, (1999). When conducting an interview there should always be some control of information exchange (Memon, A. and stevenage, S. 1996). In this case let the control of information be given to the witness.

The interviewer should facilitate the exchange of information and the interviewees will generate the information. This in actual sense does not mean that the interviewee controls the whole process of interview, it means that the interviewee control the amount of information you will acquire. It is therefore very important that the interviewer ask the right and focused questions. This ensures a smooth flow of interview that will allow free recall of events with minimized interruptions. By doing this systematic information that is arranged in a form that can be evaluated and analyzed easily will often be gotten.

The questions directed to the interviewee should be compatible. Most of questions used in interview are both closed and open. Open questions are the best type of witness compatible questions. These questions must be at level of understanding of the witness. As questions that will open the mind of witness and give the required solutions. Finally, the cognitive interview five step model can be summarized in the following sequence, ask open questions, sketch, probe, describe and the last step is advocate.

The use of rapport building Research and other evidence have shown that a good rapport with the victim as well as the witness is the most significant tool of the interviewer in the interviewing (Akchurst, et al 1997). The victim and witness need to be comfortable with the setting of interview structure. Actually, the more at ease the victim or witness is with the interview environment, the greater the possibility that she/he will be able to engage in the interview process (Stacey, H. 1997). Cognitive interviewing technique offer techniques to create rapport with the victim as well as witness all throughout the interview process. The frame work for cognitive interview is interviewee centered. It actually allows the interviewee to talk openly without fear of criticism or judgment (Memon, A. and stevenage, S. 1996). By use of cognitive interview you will always be sure that you maximize the reliability and relevancy of the information gathered when interviewing.

The cognitive interview draws the rapport of the victim by explaining to the victim the purpose of the interview, introducing everybody to be involved in the interview, explaining procedures as well as inviting any questions. This always makes the victim or the witness comfortable to speak with less reservation. Memory process By its nature/structure cognitive interview is designed to trigger the memory so that it can recall with more accuracy the relevant information on the issues concerning the sense of the criminal activity concerned.

Cognitive interview is based on psychological theories. From the psychological theories, it is argued that a retrieval cue reinstatement of the original encoding context increases the accessibility of stored information in the mind (Clifford, BR and Memon, A 1999). They further suggest that rather than having memories of discrete and unconnected incidences, our memory is made up of network of association and consequently there are several means by which a memory could be viewed.

From the above theories it can be established that if information cannot be accessed by one retrieval technique then it can be accessed by another method. The memory stored in the memory sensory nodes can be retrieved by systematic process, which involves triggering the memory reservoirs. The cognitive interview basically is designed to access memories from the deepest corner of the reservoir and bring it as evidence for victims as well witnesses. Communication skills used when interviewing Effective communication between the interviewer and interviewee form an integral part of the investigative interview process.

The use of trickery, deceit and other methods that build up psychological pressure are no longer useful in interviewing as research and other evidence indicate. The interviewer should try to bring to the interview some natural skills which she/he should adapt as the circumstances in the process of interview may demand. An interview should always be prepared carefully beforehand in order to establish the effective communication strategies which can assist in allowing for smooth information exchange between the interviewer, victim as well as witness.

The interviewer should always put allegations clearly and calmly to the victim (Huff, C. et al 1996). They should never jump into assumptions about what the response of the allegations should be since this could be misleading (Alper, B, 1995). The interviewer should listen to the interviewee side of the story. Also the interviewer is supposed to let the victim or witness take the control of information exchange. All the same the interviewer should challenge denials which are made by the interviewee when they do not square with the available evidence.

And without hurrying and bullying the interviewer should retain firm control of what is taking place. The interviewer is always required to possess well developed communicative and social skills, a calm disposition, a patient temperament, subtlety as well as ability to respond quickly. Additionally, flexibility, legal knowledge and some fair imagination are some of core factors that are key to successful interview process. Cognitive interview puts forth the best communication skills which are directed towards attaining a smooth flow of the interview process.

The cognitive interview model principles are structured to enhance maximum recall. The principle of context reinstatement normally sets the scene for the interview. This is the same principle that tries to get the witnesses to put themselves back into the event by picturing it in their mind. To accurately tap the information stored in different sensory nodes, the cognitive principles tend to trigger this information by allowing the interviewee to explicitly recall from the relevant mental imagery (Huff, C. t al 1996). This is achieved by asking questions which will tend to make interviewee describe the exact scene of the incident. The victim through extensive and varied retrieval is given opportunity to recall the incident. This is always achieved by asking the witness or victim to draw a sketch of the scene. In the same way, descriptions needed are obtained by asking the interviewee to accurately describe the visual characteristics of some objects.

For instance if the interviewee is to describe in detail the visual characteristics of a person present. The more chances a victim or witness makes to recall an incident the great the likelihood that they will remember. Cognitive interview is underpinned by its principles. The cognitive interview principles are designed and focused on consideration for a potentially difficult social interaction. The principles of cognitive interview technique model technically alleviate most of the problems which are encountered in the traditional techniques.

Cognitive interview aims to maximize the amount of information obtained by basing on the principles of psychology and communication skills which allows the interviewer to tap into how the information is stored in the memory. By use of context reinstatement, extensive and varied recall, concentration, mental imagery as well as witness compatible question the interviewer is able to maximize the reliability and relevance of information gathered in the investigative interview process (Clifford, BR & Memon, A (1999)).

In fact both the cognitive interview and its principles are in joined in a frame work that is interviewee centered. This framework promotes effective interviewing. Conclusion Research and other evidence have shown that the traditional techniques which were formally used in police interviews have many shortcomings. This is because the traditional methods frequently used jargon and leading questions as well as relying on questions and answer interviewing style. This led to misleading information which normally brought ramifications to police and beyond.

Cognitive interview offers an investigative interview process. It draws its rationale with reference to legal, linguistic, anthropological as well as eye memories interactive were necessary. Cognitive interviewing is one of the best interviewing practices eliciting relevant and effective information that can be used in handling the cases in criminal and therefore leading to rightful conviction. It has therefore met the demand for effective interview technique in police interviews.

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Scientific Investigation. (2016, Apr 13). Retrieved from

Scientific Investigation

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