Osmosis+and+Diffusion

= Osmosis and Diffusion =
 * Grade Level and Topic: ** Grades 6-8

Troy Deveney __ twd122@psu.edu __ Amelia Ahnert __ aea5125@psu.edu __
 * Names and Contacts: **


 * Educational Standards: **
 * 3.3.7B- ** Describe the cell as the basic structural and functional unit of living things
 * 3.5.7D- ** Explain the behavior and impact of the earth's water systems especially comparing the effect of water type on the life contained in them
 * 3.7.7B- ** Use Appropriate instruments and apparatus to study materials
 * 4.1.7C- ** Explain the effects of water on the life of organisms in a watershed

As a result of this lesson students should Be able explain how particles diffuse through the environment Relate this concept of diffusion to water and cells Describe how and why water moves in and out of a cell Utilize a conductivity meter to measure the salinity of water Utilize a scale to take measurements.
 * Instructional Objectives: **

In order to teach this lesson it is necessary that students have an understanding of the cell theory of life. Students must understand the phases of matter, and a observational understanding of diffusion is also beneficial. Observing the principals of diffusion and applying them to the biological implications presented by the cell membrane is the essential content of this lesson. The Students will observe diffusion through the release of a fragrance. This diffusion will then be discussed. The lesson will then shift to a discussion of how particles move inside cells. The gummy bear example will be used as an instructional tool. Finally the experiment will show the principles of osmosis by the change in weight of carrots in different salinity's of water. The presence of particles will be measured by a conductivity meter. This will be followed by discussion and explanation.
 * Content Explanation: **

To make this lab easier for all students to use, we are going to break the students into two groups. Each group will have their own computer, water samples, scale and conductivity probe. This should allow each student ample time to use the materials, decreasing any feelings of not being involved. There are no chemicals or hazardous materials being used in this lab. It is important to tell students to be careful with water around electronics and to make sure they do not consume food. This lesson uses different learning strategies including verbal instruction, discussion, demonstration, and experimentation in an effort to include multiple types of learners. Students will record their observations on a worksheet. The observational nature of the lesson should facilitate the understanding by ELL/ESL students.
 * Administrative Considerations: **

Fragrance Worksheet to record data and observations (1 per student) Gummy Bears before and after being placed in water Distilled, Tap, and Saturated Solutions Carrots thinly sliced Conductivity meter (1) Scales (1) Containers for water (2)
 * Materials, Equipment, and Set Up: **

Carrots will be thinly sliced and the experimental set up ready when students arrive. Gummy bear experiment will be done in cooking show fashion and be ready to show.

Fragrance Questions: Explain how you think your sense of smell works? How does the fragrance interact with your nose? And how does the smell (fragrance) get to your noses? To student responses, ask "how do they know this?" What evidence do they have that this explanation works? Ask for examples (smelling dinner, animals can't sense you if down wind of them). Gummy Bear Questions: What do you think will happen when a gummy bear if we leave it in water (color/size change)? Why does this change occur? Carrot Experiment Questions: What will happen to the carrot if we place it in water? What will happen if we put it in water with different amounts of solutes? What is the carrot made up of?
 * Body of Lesson: **
 * a) Engagement (2 min) **

Due to time constraints, the students are asked to weight out the carrot slices and places them into the water and salt water solutions first. They are also asked to make a hypothesis on what will happen to the carrots in each solution. They will be told that we will come back to this later and see what happens. Fragrances will be released to begin the observation of diffusion. Students are asked to make observation on what they notice and write them on the given worksheet. They are also encouraged to explain their ideas to the group. To engage the students in a discussion of how particles move in cells, a gummy bear example is used. By comparing a regular gummy bear and one that has been placed in water for a while, the students will be able to make their own observations. These observations will then be linked to the topic of cell diffusion. The student are then able to do complete their own guided experiment. A conductivity meter will be used to determine the amount of particle within the water samples used. After recording their individual data, their finding are discussed among the group and final conclusions are made through the "Final Thought Question". Understanding how particles diffuse in an important step to understanding osmosis. Making the connection that particles move from areas of high concentration to areas of low concentration is essential to understand why water would move into or out of the cell. Since the cell membrane prevents the simple diffusion of ions water moves across the gradient to reduce the concentration. Gummy bears are made up of glucose, starch, and gelatin and can serve as a model for a cell. All of these components have the ability to absorb water. They are unable to dissolve so instead of breaking apart, it swells from water absorption. For the carrot experiment, students will find that the more salt contained in the water solution the less the carrot will weigh. This is because the water within the carrot cell membranes will move outside of it to equalize the amount inside and outside the cell membranes. The reverse happens to regular water because the amount inside the carrot cell membranes is less than that in the solution that it is placed in. To ensure that student are following along and are understanding the topic on an individual level, they are asked to fill out worksheets while going through the lesson. These worksheets have space for them to write out personal observations, record data on the carrot experiment, and make final conclusions about diffusion/osmosis. Ask students to come up with other experiments they could try that deal with the topic of diffusion/osmosis. Some possible ideas that could come up are "what would happen to gummy bear in salt water" and other ways to test diffusion of fragrance.
 * b) Exploration (8 min) **
 * c) Explanation (5min) **
 * d) Evaluation(5min) **
 * e) Elaboration (extra time) **