CAT #2  Background Knowledge Probe

Teacher:

Brandon Fritz

Context:

I used this strategy for three sections of an Earth Science class I am teaching for the second time. This class is new as a result of Iowa’s new Model Core Curriculum implementation that requires all schools to teach a year of Earth Science.

Background:

I discovered during my first year of teaching this course that students lacked a good prior knowledge of how fossils form and the various types of fossils. Last year, I made the mistake of diving into a unit where students were examining index fossils representative of different rock layers and students were asked to determine the Geological era and period of the rock layer. However, students had some difficulty using fossil guides and working with fossils. I also discovered this was partly due to the lack of understanding of fossils, how they form and how scientists use them to arrive at geological dates. This year, I started the unit with a couple of simple journal questions that would serve to provide me with an understanding of how much students understood fossil basics. The two questions were:

Task:

a) How do fossils form?

b) How might scientists use fossils?

Each student was asked to write answers to these questions in his or her lab book. I then had students share ideas with a neighbor before discussing these answers as a whole. I then followed this up with having students examining a cross section of sedimentary rock strata with some patterns of fossils strewn throughout the layers. I asked students what they observed and if any conclusions could be developed.

Results:

Almost all students thought the fossils were still real bone materials in the sedimentary rocks. This was insightful for me because I understood that students did not realize that if this were true, we would not have fossils due to decomposition of organic matter.

My overall conclusion to my data was that students a basic understanding of fossils but lacked a depth of understanding of the processes involved like permineralization.

Closing the Loop:

The next day, I had prepared a power point presentation that explained a dozen different types of fossils with examples. I also included explanations of how scientists use fossils to discover relationships between organisms, evolutionary trends as well as how scientists date rock layers using index fossils. I gave a practice quiz. The results of this practice quiz (and real quiz the next day) indicated the level of understanding students had developed was much better and more in depth than when we started.

Furthermore, I posted six pictures of icons that represented a different decade of time in America (Martin Luther King, Jr., Michael Jordan, Elvis Presley, etc). I asked the students to post these in chronological order. I had groups explain how this could be used to illustrate index fossils. We then discussed the criteria needed for a fossil to be used as an index fossil.

Reflection:

This assessment of probing prior knowledge did go as planned. While I initially was expecting to just give one additional day to develop student understanding of fossils, I ended up spending a total of two and a half days in block scheduling providing students with experiences to develop a good understanding of all the different ways fossils form and how scientists use fossils to understand the past.

Furthermore, I also discovered that this knowledge made the inquiry experience over the three days much more rewarding and successful. Next time, I might start with the diagram first before the two questions.-as homework the night before and give students an open ended question like, “Using the pictures of fossils in the rock layers, how might you explain something you see?” Creating an open ended question may be more revealing about what students already know about fossils. Plus, I have found open ended questions certainly generate more fruitful discussions among students.

Secondly, I would also add the formative assessment of the “exit slip” to see how students’ knowledge or understanding changes at the end of each of the first two days.

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