This lesson is based on California's Middle School Integrated Model of NGSS.
MS-PS1: Matter and Its Interactions
PE: MS-PS1-2 - Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. This lesson is specifically designed to assess the property of density of a substance.
DCI: PS1.A: Structure and Properties of Matter - Each pure substance has characteristic physical and chemical properties.
Due to the engineering aspect of this activity the following engineering design standard may also apply
PE: MS-ETS1-4 - Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.
DCI: ETS1.B: Developing Possible Solutions - A solution needs to be tested, and then modified on the basis of test results, in order to improve it.
Science and Engineering Practices: (3) Planning and Carrying Out Investigations - Conduct an investigation and evaluate the experimental design to produce data to serve as the basis for evidence that can meet the goals of the investigation.
Crosscutting Concept: Cause and Effect - Cause and effect relationships may be used to predict phenomena in natural or designed systems. (2) Influence of Science, Engineering, and Technology on Society and the Natural World (appendix J)
Inclusion of Nature of Science and Engineering Concepts. Sometimes included in the crosscutting concept foundation boxes are concepts related to materials from the “Nature of Science” or “Science, Technology, Society, and the Environment.” These are not to be confused with the “Crosscutting Concepts” but rather represent an organizational structure of the NGSS recognizing concepts from both the Nature of Science and Science, Technology, Society, and the Environment that extend across all of the sciences. Readers should use Appendix H - Understanding the Scientific Enterprise: The Nature of Science in the Next Generation Science Standards and APPENDIX J Science, Technology, Society and the Environment for further information on these ideas.
In this lesson the students will be given a styrofoam ball that would float in a container of water. Their task is to add sufficient amounts of mass to cause the styrofoam ball to achieve neutral buoyancy. The name of the lab is derived from the combination of the words float and sink (float + sink = flink). While there is no shorter word for the term neutral buoyancy, flink serves as a memorable replacement.
I run this lab BEFORE I have taught the students about neutral buoyancy. I find that this activity is simple enough for the students to grasp and it provides an excellent foundation for formal instruction.
Essentially students will attempt (through trial and error) to add enough mass to the styrofoam to cause it to become neutrally buoyant in the water. A large metal mass (55 g) is usually required to offset the large buoyant force of the styrofoam. Small magnets assist with this and create an additional point from which to attach additional paper clips. The large paper clips can be inserted into the styrofoam to serve as mass and hooks for the metal mass. The small paper clips and staples serve as small mass in order to fine tune the buoyancy.
At the beginning of each class period, before the lab has begun, each group must inventory the equipment and sigh-in on the Laboratory Equipment Check List - Flink Lab document. At the end of the period each group can only be dismissed if they have been signed-out and cleared through me. I place my initials over their names, removing them from equipment responsibility. I typically refuse to sign-out a group if the equipment is a mess and/or not put away correctly. This is a nice way to get the equipment ready for the next class period and gets the students to accept responsibility for the equipment they are using.
The Styrofoam should eventually reach neutral buoyancy.
Student Work Sample