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Mary Stallard
Phoebus H.S.

Hampton, VA

SAND STUDIES

"In every grain of sand is a story of earth." Rachel Carson

• Students examine and compare sand samples with a sample found "at the scene of a crime." They also learn the concept of placing the suspect at the scene of the crime. This activity--which takes one to three class periods, depending on preparation and follow-up activities--is most effective when students work in pairs. Each pair needs one microscope and one set of four sand cards, and each student needs a Student Worksheet and a notebook.

• To make the activity even more appealing to students' interest, make the "suspects" students in the class and take the incriminating samples from the shoes of  your more timid students.

• Students compare their descriptions with that of the sand found on the body. One sand sample must fit the crime lab's description of the sand found near the body. The sample described is a generic continental weathered quartz sample that is common almost everywhere in the continental United States. The other samples cannot match the crime lab's description (although they can and should be similar!) A match incriminates one suspect by placing him or her at the scene of the crime.

• To give students a good idea about Holmes' deductive abilities, begin by reading aloud a

passage or two from a Sherlock Holmes book. Suggested readings are the introductory

parts of "A Study in Scarlet" and "The Adventure of the Speckled Band"

• Having students follow the steps in the Procedure section of their worksheet and answer

the questions in the Process section will provide them with knowledge of Holmes' logical thinking methods and an introduction to forensic science. The extensions suggested at the end of the worksheet make good extra credit projects or activities for students who want the additional challenge.

STUDENT WORKSHEET

          SHERLOCK HOLMES: THE BODY ON THE BEACH

Background:

Sir Arthur Conan Doyle received his training as an eye specialist at the Edinburgh Infirmary as a student of Dr. Joseph Bell. He began writing Sherlock Holmes stories to fill time between patients. Many believe the Holmes character was based on Doyle's mentor, Joe Bell.

Sherlock Holmes became the world's best known detective. His activities have been followed by millions of readers delighted by his ability to solve crimes through an amazing use of observation and deduction. Holmes drew incredible conclusions from minute details, such as a ticket fragment of a spot of mud or sand on a boot. His amazing powers of concentration and broad knowledge of science also helped him solve many mysteries. Dr. Watson, Holmes's physician friend and assistant, observed in A Study in Scarlet that Holmes had a knowledge of

            "Geology--practical, but limited. Tells at a glance different soils from each other.  After walks has shown me splashes upon his trousers--and told me by their        colour and consistence in what part of London he had received them"(Doyle,1930)

Though Sherlock Holmes was a fictional character, H. Gross incorporated Holme's methods and ideas into the rapidly developing field of forensic science in Criminal Investigation, a handbook for investigators.(Murrary and Tedrow, 1992). Literature affects science!

Problem:

The victim  of a brutal murder was recently found on a beach. Police detectives gathered small samples of sand from the murder scene and rounded up four suspects within a week. Each suspect had a motive for the killing and sand on his or her shoes. Each suspect swears that he or she was not near the murder scene at the time of the crime or at any recent time. Your job is to identify the murderer by proving that one of the suspects was at the scene of the crime. To do this, you will need to determine that the sand from the killer's shoes matches that from the murder scene.

Procedure:

•     Copy the description of the sand found near the body (See following). Looking back through your class notes, define each term in the description.

•     Examine sand from the shoes of each suspect at 20X magnification. Beside each suspect's name, write words that describe the sample and be sure to mention characteristics like size, color, transparency, roundness, and sorting.

•     Compare these descriptions (from question 2) to those of the sand found near the victim. Name the guilty suspect and give reasons why the sand from his or her shoe is the same as that found near the victim.

•     Describe how the sand on the other suspects' shoes is different from the incriminating sand.

Sand Description from Crime Lab:

Weathered granite sand consisting largely of well-sorted grains of quartz (transparent,

colorless, and slightly rounded) with trace amounts of other minerals.

Process Questions:

1. How was the incriminating sand different from the other samples you examined?

2. Why does knowing the suspect was at the crime scene make him more suspect?

3. Why must forensic geologists be extremely careful in their observations and conclusions?

Extensions:

1. Read Sherlock Holmes books or stories by Sir Arthur Conan Doyle.

2. Write a mystery story or place using scientific crime solutions.

3. Write a report on a crime that was solved using forensic geology.

4. Calculate and graph the percentage of mineral grains of other colors in sand samples that are predominantly clear quartz.

"In every grain of sand is a story of earth." Rachel Carson