Diffusion

LESSON PLAN 2 Author: Louphelia B. Mathis - Thurgood Marshall Middle School- Camp Springs, MD Western Maryland College - Westminster, MD Summer - June - 1999

 

GRADE LEVEL: 7 - 8

DURATION: 45 minutes

OVERVIEW: (See Lesson Plan - Day 1 on OSMOSIS) Students should know:

• definition of osmosis
• an explanation of osmotic pressure
• comparing and contrasting : hyperosmotic, hypoosmotic, and isosmotic
• the differences between permeable membrane, semi-permeable membrane, and impermeable membrane

   

DESCRIPTION: This activity will help students to understand the link between OSMOSIS and DIFFUSION and how they both can reach

a state of equilibrium in a uniformity distribution of molecules, either through a solution crossing a membrane or in a gaseous state of matter.

PURPOSE: To demonstrate with students the link between osmosis and diffusion, but to reinforce how each is related to our bodies and

to our environment.

OBJECTIVES: Students will be able to :

• compare and contrast osmosis and diffusion
• compare and contrast diffusion in a solution and diffusion in a gas

WARM-UP ACTIVITY: Write in complete sentences.

Explain the difference between a solute and a solvent in a solution and how each is involved in osmosis.

Teacher will engage students by saying: " Today you will learn about one of the many processes that your body under goes everyday . By the way, that is that odor I am smelling? It smells like fingernail polish. Who has the finger nail polish? The polish was broken in the back of the classroom. However class, this is perfect! Who can explain why everyone is smelling the fingernail polish now?" (answers will vary)

VOCABULARY WORDS: diffusion and passive transport

TEACHER and students will explore using of the Video Flex Microscope. Students will be asked to observe and explain what will happen when a green ice cube is placed in a beaker of cold water.(Students will observe and answers will vary). Now, a green ice cube is placed in a beaker of hot water. (see diagram- answers will very)

Teacher will explain and elaborate the process by gathering students in their lab groups. It is important that students be familiar with their responsibilities and also keep safety at the fore front of their minds.

Diffusion

DIFFUSION

PROBLEM: How does diffusion occur?

HYPOTHESIS: (Answer will vary)

MATERIALS: dialysis membrane, bag of cooked rice, iodine solution , beaker

PROCEDURE: (Teacher will cook rice before class time).

1.Take 1/4 cup of cooked rice.

2. Cut 1 3/4 inch wide dialysis membrane into 5 inch strips.

3. Soak in water and tie off one end and fill the other end with rice.

4. Add 10 grams of potassium iodine and 5 grams of iodine to 1000 ml of water.

5. Store in bottle.

6. Place the bag into a beaker of iodine solution.

7. Wait 5 minutes and observe the rice in the bag.

CONCLUSION : Students will formulate their conclusion by making inferences and observations

1. Describe changes you see in the rice. Why?

2. Describe any evidence you might see showing that iodine has diffused into the bag.

 

Evaluation (Review):

1.Diffusion and osmosis both use the passive in their transporting of material because no energy is necessary.

2.Diffusion is the movement of molecules of a material from a region of high concentration to a region of a lower concentration.

3 Diffusion of gases ( molecules) also move for levels of high concentration to regions of lower concentration until a state or level of equilibrium occurs.

CLOSURE: A good lesson today! For homework draw a Venn Diagram and compare and contrast osmosis with diffusion

 For other resources click in to the following WEB SITES:

Cell Membrane Transport:

Assessment