PLZ ANSWER WORTH 20 POINTS!!!

Kathy washed her hands thoroughly with soap and water at the start of the experiment so they were as clean as possible. She ran her fingers through her hair, and then touched surfaces that people commonly touch, such as doorknobs, refrigerator door handles, phones, and the computer keyboard.

woman's hand touching a doorknob

She rubbed the end of a cotton swab all over her hand. She made sure to get the swab under her fingernails and between her fingers. She gently moved the swab in a zigzag pattern over the prepared surface of her petri dish, as shown in the image, and put the lid on the petri dish. She labeled this petri dish “unwashed #1.”

zigzag pattern on petri dish
Then she washed her hands with hand soap, following the recommendations from the Centers for Disease Control and Prevention (CDC).

woman washing her hands

She picked up a new cotton swab and ran it all over her hands, between her fingers, and under her nails. She rubbed the swab in a zigzag pattern over the second petri dish and covered it with the lid. She labeled the petri dish “soap and water.” She stored these Petri dishes at room temperature.

The photographs show these Petri dishes after 24 and 48 hours. Write down your observations.

four Petri dishes: at 24 hours unwashed #1 shows some growth, soap, and water shows none. At 48 hours, unwashed #1 shows a large amount of growth, soap, and water shows very small dots of growth