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7th Grade Integrated Science (ALPS)Standard 1, Objective 1

Title: Diffusion in a Dish

Description: An introductory diffusion activity.

Materials: petri dishes (unsterile) water, beakers, food coloring in dropperbottles, laminated circles the size of the petri dishes(see below for sample, theydo not have to be laminated but they will last longer if they are), student page(see below)Part 2: same as above with corn syrup, sugar cubes, salt, hot water, cold wateretc.

Time Needed: 30 minutes

Background: Students need to be reminded that both water and food color aremade of molecules. They cannot see the individual molecules but they can seethem when there are many. You might introduce this activity by spraying a strongsmelling chemical (perfume, cleaner) in the room and having students raise theirhands when they smell it. Discuss how particles are always moving.

Procedures:1. Show students where materials are located and read procedures from studentsheet.2. Allow students time to collect data.3. Discuss outcomes of the experiment.

4. Give students time to answer analysis questions and conclusion.

Scoring Guide1. Students follow procedures and collect data42. Students analyze data correctly.43. Students thoughtfully write conclusion..4

Note: the drawings below can be resized by clicking on them and dragging thecorners in or out. There are two circles on the page to save paper andlaminating plastic.

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Name___________________________________Period____________

Title: Diffusion in a Dish

Introduction: Diffusion is defined as the movement of molecules from a highconcentration to a low concentration. In this activity, you will observe themovement of food coloring as it diffuses in water.

Materials: petri dishes, water in a beaker, food coloring in dropper bottles, paperwith petri dish circle on it.

Procedures:1. Collect your materials at your table and add water to the petri dish. It shouldbe nearly full.

2. Place the petri dish over the large circle.3. Notice the time and add a drop of food coloring to the center of the petri dish.4. One minute later, draw in your data the location of the food coloring.5. At three minutes, draw again.6. Draw again at 5 minutes7. Draw again at 8 minutes.8. Clean up by pouring the water back in the beaker to carry it to a sink.

Prediction: How far will the food color spread in 8 minutes?

Data:

1st minute minute 3 minute 5 minute 8

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Analysis

1. Describe the movement of the food coloring.

2. Why did the food coloring move?

3. What are molecules always doing?

4. What is diffusion?

Conclusion 2-3 sentences about what you learned:

Diffusion in a dish part 2

For this part of the experiment, you will use the above experiment as yourcontrol. You will need to change one aspect of the experiment in order to speedup or slow down the rate of diffusion. Write up the materials needed, and yourprocedure in a step by step format and include all details. Create a data table torecord your observations. Once your experiment is complete graph the results ofthe control and your experiment. You must perform you experiment at least threetimes to ensure accurate results.

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Materials:

Data table:

Graph