Directed Paraphrasing Assessment for Osmosis.

Teacher:

Michelle Hammond

Context:

After spending several days reviewing cell structures and functions we began our discussion of diffusion. This is an extended investigation that takes several days of observations

Background:

I chose my second period advanced class for this PA because these concepts tend to be difficult for middle school students and I felt these students would be able to articulate their ideas better during the interview section of the PA. Data were recorded on a data table designed by the students. At this time I discussed the student’s observations with them. What happened to the egg? Did the mass increase or decrease? What about circumference. Where did the foam come from?

Task:

Data were recorded on a data table designed by the students. At this time I discussed the student’s observations with them. What happened to the egg? Did the mass increase or decrease? What about circumference. Where did the foam come from?

I chose to interview 3 students from this class. I asked them the following questions:

1.    What was the purpose of soaking the eggs in the vinegar?

2.    What was holding the egg together after the shell dissolved?

3.    What did you predict was going to happen to the egg soaked in water? In corn syrup?

4.    What did happen?

5.    What did you learn from doing this experiment?

Results:

Students were surprised that the vinegar removed the egg shell leaving the cell membrane intact. The notion that an egg is a large cell was very confusing to them. I had to dispel many misconceptions such as “it’s melting”!  Students learned that materials do move in and out through a cell membrane. They were able to see it and measure it.

Closing the Loop:

I closed the loop in the short term by having the students write a conclusion addressing their observations and data. All of this information was recorded in their lab reports. They also had to address their hypothesis and whether it was correct or incorrect. Later on we compared data between lab groups to see if the measurements were similar and if the same patterns of mass and circumference were observed by the students.

Reflection:

I learned from this PA how important it is to take the time to make sure ALL students understand the concept being taught. When teaching things with paper and pencil only many students get left behind. I am learning how to incorporate these types of assessments into my lesson so I can individualize instruction but keep everyone busy. I am trying to teach my students how to eliminate down time.

Source:

Angelo, T.A. & Cross, P.K. (1993). Classroom Assessment Techniques (2nd ed.). San Francisco: Jossey-Bass.

Acknowledgement: The author completed this assessment while a student at Montana State University