Standard III Students will understand the structure of cells and organisms.
Objective 1: Observe and describe cellular structures and functions.
Indicator d. Model the cell processes of diffusion and osmosis. (1e, 2b, 4f)
Intended Learning Outcomes:
1 e. When given a problem, plan and conduct experiments in which they:
› Collect data on the dependent variable(s).
› Select appropriate format (e.g., graph, chart, diagram) to summarize data obtained.
2 a. Provide relevant data to support their inferences and conclusions.
4 b. Raise questions about objects, events and processes that can be answered through scientific investigation.

Background:

Students should understand general concepts of diffusion.
See Move ‘em out and Diffusion from a Balloon.

Time Required: 15-20 minutes

Summary: Diffusion is the movement of particles from a high concentration to a low concentration. This lab will provide a visual representation of diffusion throughout the classroom. Students will draw a seating chart of the room. The teacher will release an odor that could travel throughout the room. The students will write down the time that they smelled the odor on their seat in the seating chart. Then, they will gather data from the rest of the class and connect the points of equal time.

Materials:

• Something with a strong odor (Perfume, cologne, dish full of onions, ammonia, vanilla, etc.)
• Graph paper

Procedures:

1. Hand out graph paper to students
2. Have students draw a seating chart of the room (make sure they know where they sit)
3. Release the odor into the room
4. The students will time from when the odor was released until they smell the odor
5. The students will record the time that they smell the odor on their space on the seating chart
6. When the class has finished, the teacher will have each student call out the time they got at their desk and the other students will record those times on their chart.
7. The students will draw curves to connect the points of equal times.

Sample Seating Chart Data Table:

 1 min 45 sec 30 sec 3o sec 45 sec 1 min 1 min 10 sec 50 sec 45 sec 45 sec 50 sec 1 min 10 sec 1 min 20 sec 1 min 10 sec 1 min 1 min 1 min 10 sec 1 min 20 sec 1 min 30 sec 1 min 20 sec 1 min 15 sec 1 min 15 sec 1 min 20 sec 1 min 30 sec 1 min 45 sec 1 min 35 sec 1 min 25 sec 1 min 25 sec 1 min 35 sec 1 min 45 sec