Blood stain analysis is the meat of forensic studies. While most forensic blood stain analyses use uncommon or expensive chemicals, students can test for the presence of blood with a common household chemical. When students place a few drops of hydrogen peroxide on a blood sample, it bubbles profusely. This reaction indicates the presence of catalase, an enzyme found in blood. One of many possible activities with blood stain analysis is to challenge the student to test several samples with hydrogen peroxide for the presence of blood. A parent stains index cards with beet juice, tomato paste, and uncooked chicken or beef blood, and the student tests each for bubbling action and writes down his conclusions about each.
Chromatography is but one of the arsenal of forensic tools available in a criminal lab. Fortunately, simple paper chromatography is something any student can do with common household supplies. One chromatography activity involves testing the chemical compositions of various inks. The student draws a pea-sized dot of ink onto the top 1-2 inches of a paper towel. Starting at the bottom, the student lowers the paper into a cookie tray full of water until the sheet is soaked to a spot about 1/2-inch below the ink. The ink should separate and spread across the sheet with capillary action, showing the density of the chemicals that comprise it. The student repeats the entire process with different pens until each has created a series of streaks. Using these as a guide, the student can tell which pen a letter has been written with simply by analyzing the colored streaks it leaves behind.
Almost every crime scene uses the forensic tool of fingerprint analysis to narrow down a list of suspects. Students can perform many activities at home with readily available materials. A student can create a fingerprint profile database of family members with crushed graphite rubbed over fingertips and then captured under strips of transparent tape. CSI-style fingerprint activities are easy and informative as well. Students can expose fingerprints from pens, glassware, silverware and surfaces with a light dusting of almost any fine powder, such as flour or powdered sugar, and lift them with clear tape. Make sure the student places the tape on a colored piece of paper to provide high contrast between the raised and lowered areas of the print.
Forensics covers a broad spectrum of scientific methods. However, tools like the Internet provide a broad selection of curriculum related to crime scene science. Among these activities, impression evidence, witness testimony and crime scenario activities are best suited for at-home use because they require little to no expense and involve common household items. However, with an investment of about $10, students can perform forensic activities, such as extracting DNA with materials from a grocery store or creating facial reconstructions with modeling clay. Ultimately, only a handful of forensic activities are truly out of reach of a creative student with the desire to learn.