Active Learning: Engaging Students in Marine Sediment Classification

MARGARET E. CROWDER ( is an instructor of geology in the Department of Geography and Geology, Western Kentucky University, Bowling Green, Kentucky.

Teaching oceanography at an inland university can be challenging, as some students havenever visited the coast. The location also creates a barrier to the conventional idea of hands-on learning for oceanography, as a coastal field trip is an expensive prospect. However, active learning involving hands-on activities is known to improve student outcomes, with research finding increased student pass rates and conceptual understanding (Freeman, et al., 2014; McConnell, Steer, and Owens, 2003). It is therefore important to find ways to engage students outside of a traditional lecture.

Although incorporating active learning into a classroom may seem like a daunting challenge to those educators grounded in lecture-based instruction and there exists some instructor and student resistance to the incorporation of active learning into traditional classrooms (Henderson and Dancy, 2008; Waldrop, 2015), active learning does not have to involve an all-encompassing, semester-long projector series of projects. Active learning may be incorporated into a classroom one small activity at a time.

The classroom exercise described here provides an active approach to teaching marine sediment classification to students who do not have immediate access to an ocean. While I use this activity in an oceanography class, students are expected to have taken an introductory physical geology course and laboratory, and thus to have some basic knowledge of geology prior to this activity.

Getting Started – It's a Puzzle

A major classification scheme for marine sediment deals with the specific source areas of lithogenous, biogenous, hydrogenous, and cosmogenous origin. To get students thinking more deeply about the importance of source areas and sediment types, the use of coastal sediment in the classroom may be beneficial.

For this exercise, students are separated into groups, with each group given a small sample of coastal sediment (generically labeled). Samples may come from any location provided that the samples have enough sediment diversity to allow students to differentiate potential beach source areas. (Table 1 provides a description of sediment samples used in this activity.)

Along with the samples, students are provided a simple worksheet prompting information for each sample on sorting, maturity (the length of time that the sediment has been in the sedimentary cycle; texturally mature sediment is well rounded), composition and other interesting characteristics. Students are also given a combined list of potential locations for samples. The goal, and the puzzle for the students, is to match each sample with its beach location.

Students are encouraged to use a binocular microscope (if available), hand lenses, and dilute HCl to aid with identification. Figures 1-3 show samples as viewed through a macro lens (all samples are in the medium sand-sized range). Groups trade samples until each group has worked with each sample. Once each group comes to preliminary conclusions regarding the source of each sediment sample, the instructor conducts an in-class poll to determine any similarities or differences between group interpretations. At this point, students begin asking for confirmation of their ideas and solutions and the classroom gets a little raucous, in a good way, as students are surprised when they are not given answers at the end of class.

Activity Expansion

After the initial class meeting, students are directed to research possible source locations and reconsider their answers. Sometimes, students are so interested in researching the end locations for the beach samples that they may not be thinking as critically about source areas and transportation processes, so it can be helpful to give them a nudge in this direction.

For the next class, students return to their groups and share what they have learned from their research regarding possible source locations. The instructor does another poll and asks for specific group hypotheses providing sample identification and reasoning. Each group is then told how many samples they have right/wrong. Students are given access to samples again, and groups are encouraged to work together to refine their hypotheses.

All through group work, the instructor may ask guiding questions, such as: "What type of source area would you expect for a sample of that composition?" "Did you see any interesting characteristics in that sediment sample that might point to a specific location of deposition?" "How does sample [x] specifically differ from sample [y]?"

Eventually, students hone in on the specific aspect of each sample that matches it to its source, and through peer discussion in and between groups, students agree upon the appropriate solutions and solve their own sediment matching puzzle.


Student response to this activity tends toward both excitement and frustration. As is typical of active learning environments, student situational interest is likely high, as it peaks through both group learning and puzzle-type activities (Mitchell, 1993). Through extending the activity into a mini-research project, situational interest may expand even more through active student involvement in the collection of knowledge. This could lead to increased academic performance for the students (Rotgans and Schmidt, 2011).

Although a systematic assessment of student outcomes from this activity has not been completed, general student recall, identification, and situational application of associated material on exams has been positive. There is also evidence that students remember this exercise into the future, as the course instructor has received sediment samples collected by former oceanography students who specifically mention the potential for use of their sample in this activity.

The integration of a hands-on, sample-oriented active learning exercise into an oceanography classroom can be easily and cost-effectively completed through the use of coastal sediment, a hand lens, and a small amount of dilute HCl. Students interact with physical materials, conduct informal research, and engage in peer discussion and learning, while developing connections between prior knowledge and newly introduced situations and concepts. Students also appear to demonstrate higher situational interest pertaining to the activity that may extend forward by a semester or more.


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