As the last part of our ocean engineering unit, second graders are tying in all that they have learned about mass, volume, density, sinking and floating into their last design challenge.  They have also discovered that sometimes people are used in addition to submersibles to collect data.

Using a Barbie or Ken doll, second graders turned the doll into a scuba diver, making the doll sink and float.  Using the engineering design process, teams of students changed their designs test after test.  Sometimes students had to add rocks to give the Barbie/Ken more mass to sink.  Sometimes they had to add more balloons and air through the plastic syringes to get him/her to float back up to the surface.  Way to go second grade!!!

Just like real engineers, second graders are learning an important skill...to argue.  Arguing doesn't always mean yelling and fighting, but it also means to support or defend a choice.  As we wrap up our unit on ocean engineering, 2nd graders are arguing about which design to use for a submersible.  They had to compare two designs and choose which design would be "best" for the ocean engineer to use to collect data.  

As second graders improve their submersible designs, they are really starting to evaluate their designs from a deeper perspective. 

• Should they add more instruments to collect more types of data? 
  
• Should they take away instruments to reduce the size of the submersible to be able to fit into smaller areas?
  
• What instruments should they add to guarantee their submersible still floats after it collects rocks from the bottom of the ocean?

The conversations in class have been mesmerizing!  Second graders are really weighing their choices to determine what is "best."  While some students think adding more instruments is better, other students would disagree.  The argumentation has been wonderful to witness!

Can you see the student observing if her team's submersible still floats after collecting the package from the bottom of the ocean floor?  She watches from the back of the testing tank!

Teams of second graders are planning out their submersible designs, determining what size cave their submersible could fit into, and the number of packages that it can collect.  With each try, they are trying to improve one of these factors.  What if they add another instrument?  Will it still float?  Will it fit into a small cave?  Question after question abounds and improvements are made!

Now that second graders have compared the mass and volume of each instrument to one another, they are examining a very important property of each instrument--its density!

We have defined density as how packed something is.  In a sinking/floating test, second graders are seeing how this property affects the test's results.  They are testing each submersible and recording the results in their notebooks.  This way, when they go to design their submersibles, they will have all the data they need!

After second graders determined the mass of each submersible instrument, they compared them in a different way...by the amount of space they take up, or volume.  They separated the instruments into two groups:  big volume or small volume.  We added this comparison to our graph comparing the masses of each submersible instrument.  

Our next steps will see how both the mass and volume of each instrument relate to its density, and ultimately whether each instrument sinks or floats in water.  Our submersibles need to float in order gather the data they collect back up at the surface.  But the more instruments we have, the more types of data we can examine.  Submersible design challenge here we come!

As second graders prepare to create and test their own submersibles to gather data from the ocean floor, it is important that they begin to see the relationships that exist between mass, volume, and density.  Second graders first focused on determining the mass of each instrument that can be included in their designs.  Each instrument was represented using a transparent vial filled with a different amounts of pony beads, marbles, or sand.  Using two-pan balances, students learned that some instruments have more mass than others.  Will this affect their submersible designs' ability to sink or float?  We will just have to wait and see!  

So before we design a submersible to explore the ocean floor, we better know what the ocean floor looks like!  We wouldn't want a thruster to drive a submersible into a large rock or an underwater cliff.  

One kind of technology that ocean engineers have designed is the sounding pole.  The sounding pole is placed into the water and when it hits the bottom of the ocean floor, a color-coded key tells us how deep the ocean is at the point the sounding pole was placed.

More advanced than the sounding pole is sonar!  Sonar uses sound waves to map the ocean floor, giving us a more accurate representation.  Click here to find out more about sonar technology.  

Living in Greece, Despina is surrounded the ocean.  After her cousin loses her goggles in the bottom of the ocean, Despina tries to retrieve them herself.  Unfortunately, they are just out of her reach and she returns to the surface out of breath!

Despina's cousin, Nikolas, is an ocean engineer and teaches her about submersibles.  Each submersible is designed to have specific instruments which help both scientists and ocean engineers collect data about the ocean.  Realizing one of the instruments is a manipulator arm, Despina connects this idea to possibly designing her own submersible with this very instrument.  This way, she can get the goggles she lost! 

Using the engineering design process, and learning about how changing the density of the submersible enables it to sink and float, Despina gets the goggles back because of her problem-solving approach!