This video is a great resource that informs students of different types of dunes and understanding how plants help dunes become stable, which helps satisfy the last part of the standard. It also helps to transition them into understanding how specialized parts of plants help solve problems with erosion.
After we were all done with the movie, I asked them to list questions they have about sand dunes in their science notebooks under the heading " Questions to Research about Sand Dunes." I asked them to log onto a website using their iPads that has loads of information about Lake Michigan Dunes.
I wanted to have students connect the to a local area, Door County and our beautiful Lake Michigan. I asked them to scroll down the page until they found Whitefish Dunes State Park and asked them to click on the link to view the dunes that occur in our own state. I stopped them after about 7 minutes and I asked them if they could tell from the photos if the dunes were active dunes or scrub dunes?
Students shared that they thought there were both kinds there. I explained that the ridges near the area also were like rolling scrub dunes in different levels, just like it had been tilled in that shape. I explained that yes, there were both kinds of dunes there and that it is a great place to visit!
Students wanted to know if the dunes ever flatten completely out from big storms. I said that I doubted that any one dune would flatten completely. The beach was flat because of the waves pounding the sand down, but the dunes beyond that were able to rise up because the wind actually builds the sand up and then blows across the tops, changing them again.
I asked them if they would like to make some dunes right in the classroom? And so we moved on to our investigation...
Materials for Each Team: Interactive Notebook, 1/2 cup of dry play sand each, 1/2 cup of wet play sand, plastic cups for the sand, an oblong tray or paper plates, timer, a metric ruler, goggles and a wind source. Breath and blowing work just fine if cans of air are not in the budget! Fans tend to blow it all over the place.
I posed this question to my students: So what if we could create an active sand dune model in our classroom? What could we learn about sand dunes by creating this model? How would we go about creating a model sand dune?
I explained that I was going to give them a shallow tray and some sand. Their task was to create an active sand dune and show me how wind would affect the height and shape of the dune. They also need to demonstrate how moisture would affect the impact of wind erosion and prove their evidence using measurement in the best unit (either mm. or cm. )
I told them they needed to develop 3 questions that pertained to what they wanted to know about their sand dune.
They were instructed to draw, measure and create their own investigation that would be measured three times to demonstrate that change took place by wind. I told them that they must use a timer in their investigation and to create a chart that would show their data results. They were also instructed to show three sketches of each time the dune was exposed to wind. Goggles must be worn to prevent sand from entering the eyes.
I divided students into teams of 3 and gave them their materials. We discussed their predictions and coached them to develop their hypothesis by questioning their thinking. They began making and measuring the dunes.
I roved the classroom, questioning them about their thinking and asking them to make observations about the differences between wet and dry dunes. Students timed each other blowing the dry sand and measuring the data afterward. I engaged them in dialogue about their observations, as shown by this student talking about a change in width. They did the same thing for the wet sand dunes, noting the observation in their notebooks. We spent time discussing how moisture deters erosion in order that the concepts of plants and roots help keep the moisture in the soil as well as "hang on" to rocks and soils. I also talked about how plants like moss and lichen can help break apart a rock by drawing moisture out of it.
I was careful not to impose too much of my knowledge upon them as I let them observe, create and develop their understanding of an active dune all on their own. There was no wrong way to create the dunes because they would move and change regardless if they were flatter or more cone shaped. I think this is an essential strategy that represents the heart of NGSS and inquiry based science.
When students finished their data collection, I asked them to share what they had found. Each group presented their data and showed how they had measured their dune so they could show evidence of change due to the wind. I questioned them firstly by asking," What did you notice about the dry sand?" We continued with a whole class sharing of what we noticed about our measurements. Some students created a chart in their notebooks. Others simply wrote their observations in sentences.
We discussed how we would present our data to a group of people if we were to present our findings. I reflected back to the movie where the girls had noted their data on a graph. I asked, "Would a graph be appropriate to display our data today?" Most students said yes, but some were concerned about how to do that. One student reflected on her ability to figure out how to display data and how she shared that information with her team.
To wrap up our investigation, I wanted to get to the heart of the standard by asking," How do we know that the surface of the Earth can be altered by the wind?" Students responded well with accurate answers about the active dunes and their movement from the wind. They gave examples both from their observations and from the movie how the size and shape of the dune changed as it was exposed to wind.
I asked them if they could prove from their investigation that this is a model of what happens on the Earth's surface? This was a tough question for some and I could see that they were perplexed, so I rephrased it. "Do the sand dunes change from wind blowing across them? How can you connect your model to that?"
The answers started coming easily after I rephrased it. Sometimes rephrasing a question that seemed so direct, but still evokes a level of thinking they aren't used to yet, really makes a difference in their understanding and connection.
One girl raised her hand and said, " That's kinda how the snow moves around too! Wind carves it out and pushes it around making some snow drifts really big." I smiled and was happy to see her make such a great connection!