By Sara Ipatenco | Updated Aug 30, 2022
Science fairs give children a chance to showcase their scientific curiosity and learn by doing. Exploring the world of germs offers endless opportunities—from illustrating how easily microbes spread to highlighting the importance of proper hygiene. Below are four practical, classroom‑friendly experiments that are safe, educational, and sure to captivate an audience.
Demonstrate the rapid transfer of germs in a fun, visual way. Each participant receives a small squirt of hand sanitizer or a spray of water. They then roll their damp hands in a shallow tray filled with fine glitter, which represents germs. Participants are asked to shake hands with someone who has no glitter on their hands and to touch various objects—such as the edge of the table, a purse handle, or a light switch. Observe how easily the glitter spreads to other surfaces. Conclude by reminding the audience that thorough handwashing—especially with soap—removes these “germs” and prevents disease.
Use this experiment to show that everyday surfaces can harbor microbes. Prepare four potato slices and rub the flesh side on four distinct surfaces: a door knob, a toilet seat, a kitchen counter, and a tabletop. Without touching the flesh, place each slice in its own labeled zip‑top bag. Store the bags in a dark closet for one week. Afterward, examine each slice for growth; visible mold or color changes indicate microbial presence. During the fair, the student can present the slices and explain the science behind microbial proliferation.
Test the effectiveness of common hand‑cleaning products. After washing hands with plain soap, place a small piece of skin (e.g., the forearm) into a sterile petri dish. Repeat the process after washing with antibacterial soap and then after using hand sanitizer. Allow the petri dishes to incubate for one to two weeks. The sample that shows the least microbial growth demonstrates superior germ removal. For a simpler setup, rub the same skin area on a slice of bread placed in a zip‑top bag and compare the results.
Collect samples from various surfaces to test the efficacy of hand sanitizer. Use cotton swabs to sample the cafeteria floor, a student’s desk, and a cell phone. Place each swab in a petri dish containing agar. Duplicate each swab: one goes into a control dish, the other into a dish pretreated with hand sanitizer. Incubate the dishes in a warm, dark environment for several days. Compare colony growth between the control and sanitizer‑treated dishes to illustrate how sanitizer reduces bacterial load.
These experiments combine hands‑on learning with real‑world relevance, fostering a deeper understanding of microbiology and personal hygiene among young scientists.
