Bell Work: 12/4/14•Quizlet Review–On your bell work sheet, write down the words that match the definitions

EQ & Objectives

EQ•Can we research areas of health sciences—forensic science?

Objectives

TLW:•Identify different fingerprint classes.•Identify the unique ridge patterns of a fingerprint.•Develop latent prints from a crime scene and identify the fingerprint patterns.

Latent Print Challenge

Do the substances on people’s hands affect latent prints left on surfaces?

Challenge: Your challenge is to design an experiment to see how substances on people’s hands, such as lotion, soap, and hand sanitizer, affect the quality of latent prints left on paper.

Scientific Method:• (People) Purpose

– State the problem• (Really) Research

– Find out about the topic• (Hate) Hypothesis

– Predict the outcome of the problem• (Eating) Experiment

– Plan a procedure to test the hypothesis & test your hypothesis

• (Dark) Data– Record the results of the experiment

• (Chocolate) Conclusion– Compare the hypothesis to the experiment conclusion

Complete the first three steps of the Scientific Method in your STEM notebook:

1. Write the purpose of the experiment (refer back to the latent print challenge page).

2. Complete research on the following topics:− Latent prints− Ninhydrin− Amino Acids− Amines

• Answer the following question: What could be researched in order to find out what substances on human hands could react with Ninhydrin, developing a better quality print?

• Decide what substances you want to use in your experiment. Think about common substances humans put on their hands. For example, you could use lotion.

3. Form a hypothesis: What substance on human hands will develop the best quality print?

What you should have figured out from your research…

1. Latent prints are invisible prints that have to be developed by powders, special lights, or chemicals.

2. Ninhydrin is a chemical or solution that reacts with amines or amino acids from our skin (sweat and oils) to turn the latent print purple.

3. We need to see what common substances that we put on our hands contain amines that could better react with the Ninhydrin to develop a better quality print.

List of ingredientsAre any of these amines?Hand Sanitizer

Lotion

Baby Powder

Experiment Prep1. Put on regular gloves (we will discuss nitrile gloves

later). We are trying to avoid extra prints on the index cards.

2. Each person in your group will prepare an index card for a specific group in the experiment.

• 1 control group- tests nothing extra (no substances)

• 3 experimental groups- each of these groups tests a substance

3. Each person needs to take one square index card and label it with the correct information. For example: control group- none or experimental group #1- hand sanitizer.

Experiment1. Suit up! Each person should have on the

following equipment:• Nitrile gloves—the blue ones

• Geeky goggles—sorry, they protect better from chemicals

• Aprons—tied tight

• If you have long hair, it needs to be pulled back—no exceptions!!!

• You must have on closed toe shoes and pants or a skirt that reach the ankle!

2. We will experiment outside because of the toxic fumes.

Experiment (cont.)3. YOUR TEAM NEEDS TO TAKE PICTURES

THROUGHOUT THE ENTIRE EXPERIMENT!

4. Using metal tongs/tweezers, you will dip your index card in the Ninhydrin solution until the area of latent print is saturated.

5. Once dipped in Ninhydrin, you will take your index card and place it between two paper towels.

6. Keeping the index card between the two paper towels, iron the area until the card is dry.

7. Remove the card, discard the paper towels and nitrile gloves in the large garbage can outside, and take the card back to your table for analysis.

Experiment (cont.)8. Once inside, fold your apron and place the goggles on

top of the apron for the next class.

9. Tape the index card into your STEM notebook.

10. Take a photograph of your developed print.

11. Upload the photograph to the photographer’s folder. NAME THE PHOTOGRAPH WITH “CONTROL” OR WITH THE SUBSTANCE THAT WAS ON THE HAND!

DATA:

11. Begin analyzing the fingerprint for classes and ridge characteristics.

12. Compare the experimental groups with the control group. Which group developed the better quality print? Why?

What safety precautions did we take when using Ninhydrin to develop latent prints?

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