"Does it Float?" An inquiry-based activity investigating buoyancy

This activity is primarily designed for students to improve on their critical thinking skills, scientific reasoning skills, ability to work together as a group, and to apply their content knowledge to solve a given problem. The key concepts that students will be dealing with in this activity are buoyancy, density, volume, and measurement. Certain key vocabulary terms that students will encounter are buoyancy, buoyant force, water displacement, volume, surface area, and density.

This is a whole-class inquiry-based activity that is meant to be carried out following the completion of a unit on buoyancy and density. It is primarily meant for a ninth-grade physical science class consisting of a maximum of thirty students but could be modified for larger class sizes. The time required for this activity is a standard 40-50 minute class period. The only special equipment needed for this activity is an overflow-displacement container that is capable of holding a minimum of 2-3 liters of water. Concepts that students should have encountered prior to this activity are topics such as density, volume, buoyancy, surface area, the scientific method, and measurement.

This is a full inquiry-based activity/ whole class inquiry (WCI) in which students must work together as a class to solve a given problem that I present them with. In this activity students will be working together as a class to collectively solve a given problem in the timeframe of one 40-50 minute class period. The problem that they will be trying to solve is as follows: they must successfully construct a "boat" entirely out of modeling clay that is capable of supporting at least 150 grams of cargo without sinking in a container filled with water. The students are also given the following instructions for this activity:
- You will only get one chance to test your boat in the water tank to see if it passes the test, so you must carefully design your boat so that you are certain it will support the cargo.
- You may only use a maximum of 1 bar of clay to construct your boat.
- Your boat needs to be able to float and support 150 grams of cargo. The cargo must be placed on top of your boat.
- You may use the large water displacement container to perform water displacement if you wish, but you cannot use it to perform any other tests.
- You must calculate the following and record on your data sheet: density of clay, volume of clay started with, volume of boat, buoyant force of boat, and the density of your boat. Your data must be recorded on your data sheet and given to me before the end of the class period.

Students are informed at least one day prior to the activity so that they are not caught totally off-guard on the day of the activity. It is important to note, however, that before you subject your students to a full-inquiry activity such as this it is highly recommended that you spend adequate time prior to this discussing problem solving, critical thinking, and the scientific method. Without an adequate background on the scientific method you may find that your students will approach an activity such as this in a highly unorthodox manner.
The manner in which I carry out an activity such as this is as follows. As previously stated, I always make sure to inform my students at least one day prior that they will be participating in a whole class inquiry problem on a given day. Once students enter the room on the day of the activity, I inform them that the directions to the activity are on the front table and that they have the remainder of the class period to solve the problem. Once I have said this, I then proceed to the back of the room where I then record the class on a video recorder. It is crucial that you do not assist students in completing this activity in order to maintain a full-inquiry setting. However, if you notice that one or more students are in danger in terms of safety, then you will obviously want to intervene to prevent any accidents or injuries. Any materials that may be required are supplied to the students in a certain area in the room. The following materials are supplied to the students for this activity:
1) 100 mL Graduated cylinder
2) 1000 mL Graduated cylinder
3) Large water-displacement container (capable of supporting a minimum of 2-3 L of water)
4) Metric ruler
5) 4 sticks of modeling clay
6) 150 grams of cargo
7) Balance
8) Sink for water
I also make sure to supply students with the following formulas for this activity:
* Volume of a cylinder: V = πr2h
* Volume of a square: V = L x W x H
* Volume of a sphere: 4Ï€r3 / 3
* Density = Mass / Volume
Once the class feels that they have successfully constructed a "boat" that is capable of supporting the 150 grams of cargo, they notify me and their vessel is tested in a water filled container. Once the vessel has been tested, the students then submit their data to me and the activity is complete.
On the following day, I devote at least 20-30 minutes of class time for discussion and reflection on the activity. It is during this time where I also inform the class on how well they performed on this particular activity. I also show students "highlights" of their activity that I have selected from the footage that I gathered while they were completing the activity. This allows students to see exactly what went on during the activity and usually facilitates some good discussion as to what worked well and what didn't work so well. Reflection is crucial in this activity as it allows students to improve their critical thinking skills and make suggestions for improvements for the next inquiry activity that they might encounter. Student directions (Microsoft Word 2007 (.docx) 130kB Aug2 09) Whole Class Inquiry Assessments (Acrobat (PDF) 617kB Aug2 09)

This is a great activity in many ways, but I particularly like how it not only reinforces students' knowledge on key concepts from the current unit, but it also allows them to demonstrate their mastery of the concepts in a hands-on activity. It is also a great way to assess students on their problem solving skills, critical thinking, and scientific inquiry skills. If this is the first whole class inquiry activity that your class has experienced, be prepared to observe some pretty unrefined and unorthodox problem solving methods from your students. In my experiences with inquiry-based activities, students will often perform unsatisfactorily on at least the first activity, but will then make steady improvements as they become more accustomed to scientific inquiry and your own expectations that you have set for them. This can be a very cumbersome process, but it is also extremely rewarding once you see the drastic improvements that your students will make throughout the course of the year!
Some recommendations for this activity are as follows:
1) Make sure to complete this activity on your own at least a day prior so that you may see any areas where your students may encounter difficulties.
2) Once you have constructed your own "boat," make sure to save it so that you may compare it with your students'. This allows for some good dialogue during the reflection component of this activity.
3) If you don't have an overflow displacement container that is capable of holding a minimum of 2-3 L of water, you can easily make one with a turkey-roasting pan. Here is how I made mine:
a. Carefully cut a small hole in the front of the pan mid-way between the top of the pan and the bottom of the pan. You will be inserting a valve/nipple in this hole, so make sure that the hole is no bigger than the item that you are fitting it with.
b. Next, insert a ½" nipple or valve into the hole. This can be purchased from many local hardware stores.
c. Finally, seal the edges of the nipple/valve with a waterproof epoxy or caulk so that it doesn't leak once the pan is filled with water. Allow at least 1-2 days for the bond to harden.
4) As stated earlier, make sure not to help your students solve the problem. Doing so could severely hamper the full-inquiry environment.
5) I choose to assess my students in this activity by focusing on the following areas:
a. Safety measures followed (5 pts)
b. Participation (5 pts)
c. Procedure followed (5 pts)
d. Accuracy of data (5 pts)
*It should be noted that all students receive the same score on this activity.

In this activity all students receive the same score. I choose to do this because students must work together as a team to solve the problem, so I assess them as a team rather than individually. I also will typically make this activity be worth 1/5th the point value of the unit exam. I assess the class on four key areas: 1) Safety measures followed; 2) Participation; Procedure followed; and 4) Accuracy of data. All four areas are of equal point value.

9.1.1.2.1 – the practice of science; scientific inquiry.