Erosion and Deposition Unit:  Labs and Assessment

Heather Bradway
Hancock Middle School


I have been teaching an eighth grade Earth science class for the past seven years.  Every year, the students and I explore erosion and deposition, however I had no lab activities to reinforce their learning.  My experience on Isle Royale allowed me to reflect and develop a unit on erosion and deposition using the island's topography.

Two new labs were developed which allowed students to construct knowledge about erosion and deposition.  Both labs required the use of stream tables, which have added a completely new learning experience to my classroom.  The first lab focused on running water erosion using a simulated stream.  Students had to set up the stream table as it may appear 5000 years ago and again at 10,000 years ago.  The variable students used was the height of the stream table.  Students also needed to demonstrate the type of erosion and deposition that would occur during a flood.  

This lab activity demonstrating stream erosion was worthwhile and I plan to implement it for future classes.  Students were able to witness a change in the direction and flow of water as it progressed down the stream table over a two minute period.  Sediments could also be easily viewed depositing throughout the table.  The observations that students made were noticeable in their lab write-ups, however I'm not convinced in keeping the portion of the lab demonstrating the flood.  Next time, I will have students place objects along the stream banks and observe what happens to these objects over time as the stream flows.  Using this experience, students will be asked to apply their observational knowledge to a situation where humans are building along riverbanks and how erosion and deposition may affect these structures.

The second lab developed used the stream table to demonstrate wave erosion.  Students were asked to use the table to construct a beach.  Using their beach, students had to observe how the period of a wave affects the rate of erosion.  Students also had to construct a break wall and observe the affects that it had on beach erosion and deposition.  

This lab activity went O.K.  The shape of the stream table hindered the action of the waves erosion.   The reason I implemented this particular lab activity was so students would connect wave erosion in a stream table to what they have  witnessed while at a beach on Lake Superior.  

In either case, for each of the two new labs, students responded well. They all were able to gain experiences where they could experiment with erosion and deposition.  Photos of the students participating in the labs have been included in this summary report.

An additional assessment for student understanding of erosion and deposition was created and implemented after the unit was formally taught and tested.   I started a weeklong activity that used Isle Royale as a focal point for constructing student understanding of erosion and deposition in a real world application.  

In order to prepare students to complete the final assessment, two days were spent on looking at topographical maps which had erosional landforms on them. Students used an Internet site that I provided, which had many topographical map links, each with a different landform. They had to make a series of drawings showing the five agents (wind, running water, glaciers, gravity and waves) of erosion and the type of landform that each agent could create.

Additional time could have been given to students for this activity.  If I assign this activity again, I would reduce the number of drawings required from ten to four, focusing on quality and not quantity.  I would also include more reflective questions that would direct student thinking.  I want my students to make connections between what they see on the computer as a series of contour lines and the landforms that are present.  The goal of this activity was for students to recognize the role that erosion and deposition may play in the formation of some landforms.

After completion of this Internet activity, some students complained of not understanding what they were looking at and drawing from the web site.  These complaints told me that I needed to use the LCD projector to prepare the class prior to the activity and preview the web site to discuss contour lines and how these lines create a particular landform.

The final activity developed was a constructed response assessment using a map of Isle Royale.  Students had to look at the map and make a list of ten erosional or depositional features found on the island.  Using the list, students had to make a table of landforms, the agent of erosion which created it and had to describe the processes involved in their formation.  Students were given two days to complete the constructed response assessment.

The second half of this assessment required students to identify three erosional or depositional landforms around the Copper Country.  Originally I wanted students to find landforms only in Hancock however, students were uncomfortable with this and wanted to be able to use more land area.  I definitely will keep this portion of the assessment because it forces students to take notice and observe the world around them.

When asked which type of assessment truly measured their understanding of erosion and deposition better, most students responded that the project was a  better measurement than the test.  One student said that the project required him to apply what he knew about erosion because he would not have been able to complete the assignment if he did not understand erosion and deposition; he said that the project made him think about everything that he learned at one time.

A comparison of student percentages earned on the selected response assessment or test and the constructed response assessment or project, shows a significant difference in average scores (Table 1).  The average test score was  78 percent whereas the average Isle Royale project score was 91 percent.  Not all students demonstrated an increase in understanding.  Some student scores (4 out of 21) showed a decrease from the test to the project.  The reason for this is that the project required more higher level thinking in the synthesis realm than that of the test.

Overall I am pleased with the two new lab activites and the Isle Royale erosion and deposition project.  Continued use of the Isle Royale erosional and depositonal landform activity as well as the two labs is expected.  They allow students to apply what they have learned to real-world situations.  Hopefully students will never look at their hometown or Isle Royale the same again.

Table 1
A table comparing percentages earned by students using both a selected response (test)
and a constructed response (project) assessment for the understanding of erosion
and deposition.
Selected Response Assessment
Constructed Response Assessment
Percent Change
Percentage
Percentage
Student number
1
66
52
-14
Two students did not
2
87
100
13
complete the project
3
86
76
-10
and their percent
4
80
100
20
change data is not
5
38
0
NA
included in the table.
6
57
84
27
7
83
84
1
8
88
100
12
Average percent
9
88
92
4
decrease = 8.5.
10
88
84
-4
n= 4
11
82
92
10
12
75
92
17
13
80
92
12
Average percent
14
98
100
2
increase = 14.9.
15
73
84
11
n=19
16
98
92
-6
17
75
100
25
18
77
92
15
19
83
92
9
20
58
100
42
21
72
0
NA
22
88
100
12
23
52
92
30
24
80
100
20
25
97
100
3
n=25
n=23
average = 78%
average = 91%