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Start With Phenomena

Why Are There Coral in the Cliffs?

Engaging third graders in a historical science phenomenon

Science and Children—January/February 2021 (Volume 58, Issue 3)

By Laura B. Schneider and Kayce Wills

We encounter scientific phenomena daily, but not all phenomena can be observed when they happen. Students cannot go back in time and watch the predatory Ecphora drill into a bivalve or view living Chesapecten in the shallow marine environment of the Mid-Atlantic coast 13 million years ago. However, they can observe fossil evidence.

Paleontology falls under historical sciences, which are unique in that they utilize observation versus manipulation of natural phenomena. The historical sciences find the causes of past events, study natural phenomena that are not interchangeable, often involve qualitative data, and center on creating explanations (Gray 2014). Using fossils to study paleoclimatology is an example of historical science because fossils can be used to make inferences about the past, and each specimen is unique. A fossil may show evidence of predator-prey interactions, or its color may be indicative of a specific bedding layer. 

We describe a three-dimensional 5E (Engagement, Exploration, Explanation, Elaboration, Evaluation) lesson that investigates 3-LS4-1: Analyze and interpret data from fossils to provide evidence of the organisms and the environments in which they lived. A phenomena-based approach was used to engage third graders in the story of Maya, who walks the beach in Maryland and sees what appears to be a piece of coral in the cliff. This is surprising because Maryland’s current environment does not support coral. Maya gathers evidence that she takes home and photographs. Students are actively involved through exploring photographic evidence to determine why coral would be in the cliff and what can be inferred about the past. 

Students draw sketches of fossils and record data.

Students draw sketches of fossils and record data.

Background Information

World famous fossil deposits are found at the Calvert Cliffs on the Western Shore of the Chesapeake Bay. During the Miocene, the region was more temperate than today and was covered in a warm, shallow sea that was less than 100 meters in depth and in many areas shallower (McLennan 1971). It supported a wide diversity of marine life and most are no longer found in this region. The fossils in this lesson come from the Choptank Formation, one of three formations of the Chesapeake Group. We can infer the Choptank was shallow based on the teeth of rays and smaller sharks. In other formations, larger teeth are abundant. Presence of fossilized coral, sand dollar fragments, and sessile mollusks confirm this idea of a warm and very shallow environment.

As organisms died, they sank to the bottom of the sea floor and became preserved in layers of sand and silt (McLennan 1971). Over geologic time, sediment layers built up, creating a large package. Due to sea level change, the cliffs that were once at the bottom of the sea now stand roughly 30 meters above the water (McLennan 1971). 

Formative Assessment

Learners’ prior knowledge of fossils was assessed by examining objects such as a recent shell, a rock, a fossilized shell, a fossilized shark tooth, a trace fossil of a burrow, a piece of quartz, and a coin from the 1800s. All objects were placed on a table and students were asked to come up in small groups and examine the objects. We asked students to make a two-column chart on lined paper and write at the top the words “fossil” and “not a fossil.” Students were asked to group objects and to write in short sentences to justify their claims. Students requiring accommodations had access to talk-to -text technology that was utilized in lieu of writing sentences or were encouraged to put their ideas into a bullet list. This preassessment helped us to see that some students had a misconception and did not realize the burrow could be a fossil.


Prior to starting the lessons each day, students were given clear expectations on behavior in the science lab, including encouragement to “put a hand in the air if you want to share.” The school’s science lab allowed for up to 35 students to actively work in groups of two to three. Students were grouped based on complementary skill sets and each group was given their own randomly distributed envelope with photo evidence. Groups that included students with attention needs were placed closer to the teacher to receive extra support and to allow positive reinforcement for focus.

Students were introduced to the scenario that a young student, Maya, had sent mail with pictures of what she suspects to be coral in a cliff (see NSTA Connection). Envelopes included a letter from Maya and a series of photos that show the cliffs, shore, and fossils. Students were instructed to first take out the letter from Maya. As an accommodation, we read the letter aloud, placing inflection on certain parts to increase excitement. Students were immediately interested in the story of Maya. As a way for students to share their personal background, we asked, “who’s been to the beach?” and “what kind of things do you normally see at the beach?” Students enthusiastically shared their experiences and things they had seen including shells, sand, rocks, and crabs. 

Learners were asked to take pictures out one at a time. Students were challenged to locate the coral on the pictures. Groups pointed to a variety of things. We examined the more close-up picture and some students were surprised at what the coral looked like. We asked them what they knew about coral to assess prior knowledge. One student said that she knew that “living coral has lots of colors, but this is white.” Many students knew they came from “tropical areas” and “live in the ocean.” A data map was used to examine where coral is found globally. This verified what students knew about coral being tropical. We also asked them to point to Maryland, where Maya is from, to verify it is not currently inhabited by coral reefs. We walked around the classroom to support students with map identification.

Students engaged in the science practice of asking questions. We challenged them to develop questions based on the pictures. Student responses included “How could coral get in the cliff?” “Could the coral have floated out of the water?” and “How could a big cliff form?” Questions were written on the board and saved for use throughout the unit.

Socially Distancing

Because the authentic data that students work in this investigation is pictorial, the lesson could be modified for non-traditional classroom settings. To facilitate this, we have come up with some ideas for ways to modify this lesson.

  • Instead of having students move to the table up front to observe objects during the formative assessment, the objects could also be placed on a document camera for all to view.
  • During the Engagement portion, instead of having letters printed on paper and placed in an envelope, the documents could be shown on a screen to minimize the need for touching paper.
  • For the Exploration section, if students are working in a virtual setting, students could be placed in a breakout group and each group could be assigned one sheet of fossil data to examine collaboratively.
  • With the paper and book stacking activity in the Explanation section, the teacher could model this in the front of the classroom or on camera. For students at home, they could be challenged to come up with their own ideas of things that they could stack to represent sediment accumulation over time.
  • The Explanation activity that focused on relative dating and geologic time could be done using a Google Document with text boxes for each word or phrase that could be moved around the screen and put into order.
  • For the Elaboration section, the classroom blackboard was originally used as a focal point to centralize and record student data. In a virtual setting, a table could be made in Google Slides or Sheets and students could be given access to input their data.
  • The Evaluation portion should not require much adaptation. Though we would suggest if done virtually, have the students submit a rough draft of their drawing or letter so you could offer support and feedback before they complete their final draft. If done virtually, you could also give students the option to voice record their final assessment instead of submitting it in written format.


On the second day, each group received their own unique sheet of fossil pictures (see NSTA Connection) to describe and identify; 20 sheets were created to allow large classes to work in small groups. The investigation centered around Maya’s story. We explained that Maya knew it was not safe to dig in the cliffs, so she walked along the beach, collected evidence, and then photographed her finds for the class to study. We reiterated that Maya would like them to help figure out what she found. 

Students observed, counted, and sketched the objects on their “Cliff Treasures Data Table” (Figure 1; see NSTA Connection) as a way to “analyze and interpret data to make sense of phenomena” (NGSS Lead States 2013). A variety of accommodations were used including buddy writing, drag and drop sentence strips, and speech-to-text aids. If the class discussion exceeded the desired volume level, students’ attention was brought back with redirects popular to the school culture, including “give me a five, a four, a three, a two, a one, and talking is done” in a softening voice ending in a whisper. We explained that each group should have eight different types of specimens in their data and challenged them to find all eight; however, students with accommodations were encouraged to focus on three to four specimens. As students made their observations, we circulated through the room to provide in-the-moment feedback and answer questions, which also kept students on task.

Figure 1
Student data collection example.

Student data collection example.

Observations included comparing objects to the size of a quarter, which is using the crosscutting concept of scale, proportion, and quantity in a spatial sense. Learners would often say things like this “this shell is three times longer than a quarter” or “this tooth is much smaller than a quarter.” Observations often included prior knowledge such as “this one reminds me of a snail shell.” Students also compared objects saying, “I think these are the same because they have the same lines and they are both curly and round.” The day ended with learners sharing some observations with the class.  


The third day began with a recap of the previous investigation. Students explained they were working to help Maya learn about her beach treasures. We reiterated the research questions that students had posed: “How could coral get in the cliff?” “Could the coral have floated out of the water?” and “How could a big cliff form?” and “Has the water level changed over time?” Students shared that Maya found fossils and some knew that shells having a white appearance instead of colorful indicated they were older. We asked students to share what they knew about fossils. Students made a variety of statements including: fossils can be a marking in the ground, they can be on the Earth (surface), or in the water, dinosaurs made fossils, fossils came from animals, and fossils have been sitting around for thousands or millions of years. However, some thought that fossils could only be bones, fitting with the common misconception that only hard parts of organisms are preserved as fossils as reflected in the preassessment (Fries-Gaither 2008). If the teacher has any fossils available, they should be shared with students so they can make observations.

To help students learn more about fossils, we read Curious about Fossils (Waters 2016). While reading, we stopped to discuss the photos. An important feature of the book was the discussion of how sediment builds up layers to bury fossils and forms rocks. We reiterated the students’ question, “How could a big cliff form?” and asked students to write down answers in sentence form or pictorially. This flexibility was helpful for special needs learners such as ELL students. Students could think-share-pair for a chance to express their ideas before sharing with the class. Students explained that sand and other “sediment built up over time” and “water went away” to form the cliffs. 

To further model this idea, pieces of construction paper and textbooks were stacked to show the idea of sediment formation over time. In this scenario, the books represent sediment layers and the colored paper represented organisms becoming fossilized. Students were able to see how layers stacked up and that older layers were near the bottom. We also modeled the idea of erosion by having some students come up and remove the top layers to represent sediment being eroded over time. We asked what forces could cause erosion? Students understood both wind and waves could erode the cliffs.

Next, we defined fossils as evidence of life in the past that was at least 10,000 years old and asked students “What things could become fossils?” Students shared that things besides bones could fossilize, including shells, mammoth hair, and plants. We then returned to the formative assessment with the line-up of objects. Students were given back their original papers and asked to make another two-column chart on the back of their paper. Learners were able to correct their misconceptions with a new understanding of fossils.

Students examine a photo of a beach environment.

Students examine a photo of a beach environment.

We then discussed questions they had asked about coral: “How could coral get in the cliff?” and “Could coral float out of the water?” Students pondered these questions and applied the information they had learned. To understand this phenomenon, students needed to know that coral was once part of a shallow sea environment. Coral, shells, and other remains sank to the bottom and became covered with sand and mud which built up, eventually becoming Calvert Cliffs (Ashby 1986). A student shared “coral was alive and could be covered up by sand after it died.” This was important to understanding that sediment builds up over time and lithified into the cliffs. As for the question about floating, students said that once the cliffs were broken down, coral could end up in the water. They reasoned that they did not think the coral was a recently living organism since coral “lives in warmer climates” and living coral would look physically different from coral fossils. One learner reasoned it was more likely that “maybe the rain washed the fossil coral off the cliff and that’s how it could end up in the water.” Another learner said that “when pieces of the cliff fall down they could have fossils like coral in them and that could be how they end up in the water.” We ended by evaluating their understanding by asking thumbs up/thumbs down questions.

The fourth day began with discussion of the NGSS crosscutting concept of temporal scale. We started by writing phrases on lined sheets of paper in print large enough for everyone to see: my first day of school, dinosaurs were alive, the day my teacher was born, yesterday, George Washington was president, the day I was born, woolly mammoths were alive. Then we wrote “older” on the left side of the board and “more recent” on the right side of the board. Students were called on to come to the board and place a term in the correct order. Tape held the pieces of paper so they could easily be shuffled when students disagreed. Once all papers were in the correct order, we discussed how these events made up a time scale. 

We explained that scientists break up the history of Earth into different time periods, the geologic time scale. Students examined a handout from UC Museum of Paleontology as we asked them guiding questions. We told students all the fossils we observed were from the Miocene and were approximately 13 to 18 million years old. Students were asked to point to Miocene and then the Mesozoic since students had mentioned dinosaurs could be fossilized. We circulated the room, helping students who needed help finding the time periods and explaining the specific labels to students who needed it. Students were asked to look at the major biological events and compare which ones happened earlier and later. If the classroom has either individual computers or a computer that can be displayed on a large screen, the UC Museum of Paleontology website (see Resources) can be explored in -depth as a way to further understand the geologic time scale.


The fifth day began with a recap of the previous day’s highlights. Students again used the “Cliff Treasures Data Table” for the Elaboration portion, bringing in the new dimension of using fossil guides to identify the species by name. We told students our goal was to use the data to help Maya figure out what the Mid-Atlantic was like in the Miocene. As students worked together, we circulated to answer questions and directed students to salient identifying features. 

The lab’s blackboard was used to make a large data table that would serve as a focal point. A helpful resource was the Calvert Marine Museum’s Fossil Identification page so that as fossils were discussed, their picture could be projected. We found that it was easier to make this a whole-class activity and go through species one by one. Each group reported individually how many of a species they found. Then we shared special characteristics of the species for students to fill in on their table. Because students were working in their small groups they were able to take turns writing to make it more manageable. As an accommodation, groups were given printouts of a table with fossil characteristics to look at as the teacher read them aloud (see NSTA Connection). 

By centralizing data on the chalkboard, students could “compare and contrast data collected by different groups in order to discuss similarities and differences in their findings” (NGSS Lead States, 2013). It also gave students a chance to use the crosscutting concept of patterns to “identify similarities and differences in order to sort and classify natural objects” (NGSS Lead States, 2013). A pattern noticed by the class was that there were more bivalves as opposed to gastropods and sharks. We discussed why there were less predators like moon snails and sharks present in the environment. It is key to help students understand that predator-prey relationships are important to balancing an ecosystem. When an ecosystem is unbalanced such as having too many predators, it causes the population of the prey to plummet and then the predator population will fall. Because of this natural cycle, it makes sense that our samples would have less fossil evidence of predators than prey.

We discussed how this inquiry was different from other science investigations they had completed. Learners recounted some of their observations and we discussed the importance of observation to historical sciences. Students understood that each fossil and each group’s data set was unique, that some groups had a species present that others did not, and some had holes, which were evidence of predation. We talked about how fossils could be used to infer past environments. Fossils that were noteworthy in helping them infer a shallow tropical/subtropical marine environment were the sand dollar, coral, quahog, whelk, shark’s teeth, and ray dental plates.


For the sixth day, students were given a choice as to how to share their findings, fitting with Universal Design for Learning (UDL) Provide Multiple Means of Engagement. The first option was to draw a model of the environment during the Miocene. This allowed them to “develop and/or use models to describe and/or predict phenomena” (NGSS Lead States 2013). Students were asked to make a rough sketch and conference with the teacher to get advice and make corrections. First drafts had an abundance of sharks, not representative of their data. We asked them to look at their data and class data and make corrections before being given a second sheet of paper. Students asked insightful questions like, “should I draw plants because I know they had to be part of the environment?” This led to great discussion about how the fossil record selects for organisms with hard parts. 

The second option was to write a letter to Maya to tell her what she found and what the environment was like during the Miocene. This gave students a chance to “use evidence (e.g., measurements, observations, patterns) to construct or support an explanation” (NGSS Lead States 2013). This also allowed students to engage in Common Core writing skills.

The Evaluation portion could be modified to meet the needs of all students. For instance, instead of writing their explanation in a letter, special needs students could also prepare their ideas and share them verbally with a teacher, use talk-to-text technology, or list ideas instead of writing in complete sentences. The evaluation could also be made more rigorous to support students who may need an additional challenge. Students could be given additional data sets (out of the 20 available) to collect data and determine if multiple data sets support or refute their claims. 

Concluding Remarks

This three-dimensional lesson gives third graders an opportunity to complete an investigation using nearly 400 fossils as evidence. Students were engaged in helping Maya understand the historical science phenomenon of why there would be coral in a cliff and learning about the paleoenvironment. We believe that this lesson is a great way to introduce students to investigating historical science phenomena. ●


Clark, W.B., et al. 1904. Miocene Plates. Maryland Geologic Survey. Baltimore: John Hopkins Press.

Calvert Marine Museum. 2020. Invertebrate Fossils.

UCMP (ND). Geologic Time Scale. Understanding Geologic Time. UC Museum of Paleontology.

Vokes, H.E., J.D. Glaser, and R.D. Conkwright. 2000. Bulletin 20: Miocene Fossils of Maryland. 2nd edition. Baltimore: Maryland Geologic Survey. 

Waters, K. 2016. Smithsonian Curious about Fossils. New York: Grosset & Dunlop. 


Ashby, W.L. 1986. Fossils of Calvert Cliffs. Solomons, MD: Calvert Marine Museum Press. 

Fries-Gaither, J. 2008. Beyond penguins and polar bears. The Ohio State University. 

Gray, R.E. 2014. The distinction between experimental and historical sciences as a framework for improving classroom inquiry. Science Education 98 (2): 327–341.

McLennan, J.D. 1971. Miocene Sharks Teeth of Calvert County. Baltimore: Maryland Geologic Survey.

NGSS Lead States. 2013. Next Generation Science Standards: For states, by states. Washington, DC: National Academies Press.

NGSS Phenomena Physical Science

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