By Laura Hospitál on May 12, 2015

As students learn about plate tectonics, they are introduced to the concepts of tectonic plate movement, either away from the adjacent plate (divergent boundary) or toward the adjacent plate (convergent boundary).  When a divergent boundary occurs in the ocean, seafloor spreading is the result. Seafloor spreading is the movement of magma through a crack in a mid-oceanic ridge.  This interactive activity is simple to prepare and to execute and allows the students to understand seafloor spreading and the position of newer rock and older rock in relation to the mid-oceanic ridge.  This will also represent clearly why older rock is farther from the divergent boundary and newer rock is closer to the boundary.

The idea for this activity is from a YouTube video and was discovered by Jim Clark as he taught seafloor spreading to his 8th grade class.

Related Vocabulary:

• Plate tectonics: The scientific theory that the Earth's crust is made up of plates that slowly shift position
• Convergent boundary:  A boundary between tectonic plates in which the plates are moving toward each other
• Divergent boundary:  A boundary between tectonic plates in which the plates are moving away from each other
• Transform boundary:  A boundary between tectonic plates in which the plates are sliding past each other
• Seafloor Spreading:  Due to plate tectonics, magma at mid-ocean ridges flows through cracks and forms rock when it cools

## Preparation:

1. Using a knife or a pair of scissors, cut an 8" slit in the top of the shoebox widthwise in the middle of the box. Alternatively, the crack in between 2 desks can easily be utilized.
2. Cut a piece of cardstock or braille paper 12" X 3".  Large square braille paper is almost 12" long and can be used and cut into a 3" wide strip.
3. Bend the paper in half lengthwise.
4. Cut out 2 pieces of each of the 4 types of textured paper  with dimenstions 1.5" X 3".
5. Make 8 labels in both braille and large print as follows. (See picture below)
• Print 2 sets of 48 pt. labels with the number 1, 2, 3, and 4.
• Make similar labels in braille using braille label paper.
• Attach the braille labels to the appropriate print labels.
• Cut out the labels approximately 1" tall by 1/2" wide.
6. This model represents the flow of lava over time due to plate tectonics at mid-oceanic ridges (seafloor spreading).  The 4 tactile surfaces will represent rock of various ages depending on how long ago it was laid down.
7. Please refer to the picture as you build this model.  Using a hot glue gun, glue the textured paper to the cardboard stock choosing one texture for the two textured surfaces closest to the bend, a different texture for the next section on both sides, a third textture for the next section, and a final texture for the two sections farthest from the bend.  Use different colored textured paper for each.
8. Tape the labels on the textured surfaces from bend out to the end of the paper on each side as follows:  4, 3, 2, and 1, on each textured surface.

## Materials

• shoe box ( or the crack between 2 student desks can be used)
• scissors or knife
• large piece of cardstock or braille paper at least 12" long.
• Textured paper - Available from APH
• Braille label paper - Available from APH
• hot glue gun
• hot glue stick

## Procedure

After instruction in plate tectonics including discussion of divergent and convergent boundaries and seafloor spreading, use this model to demonstrate the location of rock which was laid down longest ago as farthest from the divergent boundary relative to the rock which was laid down more recently.  This will be accomplised using both the different textures and colors of the sections of the model as well as the numbering of the sections.
1. Slip both free ends of the paper through the slit in the box from underneath.
2. Tell students that the slit in the box represents a divergent boundary. Ask:  What happens at a divergent boundary?  Students should answer that the adjacent plates are moving apart.
3. Explain the model to the student.  Tell him that it represents seafloor spreading at a mid-oceanic ridge.  Ask what type of boundary seafloor spreading occurs at?  (divergent)    Explain that the area numbered "1" represents lava (melted rock) that flowed through the divergent boundary longest ago to then form rock.  Newer rock was laid down "2", "3", and then "4".  Tell the student that the different colors and textures differentiate the numbered sections.
4. As the student pulls the model through the slit, have him/her describe seafloor spreading and repeat the meaning of "1","2","3", and "4" as he interacts with the model.
5. For older middle school students or high school students, convection currents my also be discussed. (See definitions)

## Variations

If time is short, this activity could be prepared for a student with low vision utilizing color, rather than textured surfaces, or for a braille student using numbers in braille only.

## NGSS Standards:

4th grade - Earth's Systems: Processes that shape the Earth: ESS2.B: Plate Tectonics and Large-Scale System Interactions
The locations of mountain ranges, deep ocean trenches, ocean floor structures, earthquakes, and volcanoes occur in patterns. Most earthquakes and volcanoes occur in bands that are often along the boundaries between continents and oceans. Major mountain chains form inside continents or near their edges. Maps can help locate the different land and water features areas of Earth. (4-ESS2-2)

Middle School - History of Earth:  Tectonic processes continually generate new ocean sea floor at ridges and destroy old sea floor at trenches. (HS.ESS1.C GBE) (secondary to MS-ESS2-3)
ESS2.B: Plate Tectonics and Large-Scale System Interactions Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth’s plates have moved great distances, collided, and spread apart. (MS-ESS2-3)