Strategies
This unit was written to provide background information about nanotechnology to help educate an educator, but also to provide the reasoning and methods for the teaching of a unit on this subject.
As stated in the introduction my students will already have been exposed to Newton's three lays of motion as well as conservation of energy, and a unit on chemistry which they will have done earlier in the year. The goal is to take those principles and then apply them to this scaling down of objects.
My first step will actually be to teach some of the history about this and why we have been able to develop objects at such a small scale. This will involve a look at Richard Feynman and his lecture that inspired scientists to begin looking down in scale. Although not in this paper, but readily available, I will expose the students to the instruments that are used (such as the different forms of electron microscopes and tools that enable scientists to move particles around) and how that technology actually helped further this research.
The first step in functional science education for this is to make sure students can understand the numbers that are involved with nanotechnology as an introduction to the subject matter. They will look at everyday objects and use them to determine how large or small the objects are on different scales of measurement. The items for this may include their desk, a book, a pencil, a piece of hair, and other small objects. This will expose students to the reasons scientists work with different levels of measurement. They will continue this exploration by looking at the surface to volume ratio of these different objects based on their total size. This will then be related to coursework they have previously completed on S/V ratio and the need for energy in cells of living things. They will conclude this by looking at how many nanometers each of their objects are. This will give them a sense of how small objects in the nanoscale really are. A discussion of how much more advantageous it is to be at nanoscale with particles should follow.
The next section will look into is the physics of size change. They will look at strength to weight ratio by performing a lab. In this lab they will have dowel rods of various diameters. They will take the smallest one and determine a length (short length 5cm) and calculate the volume of the object. With this number they will need to make an accurate scale of the remaining objects so that each larger diameter will have exponential growth in their length. Once completed they will then test each object for strength by hanging weights from the rods until failure occurs and keep track of in a data table. The conclusion of the lab should show them that the smallest rod had the greatest strength to weight ratio (the greatest ratio of weight to its surface area). For more detail of this please see lab in activities section of document. A discussion of the strength of nanoparticles can follow this lab.
A discussion of Brownian Motion and Reynolds number is the next logical step. This can be done in discussion with demonstration or a lab can be developed. Viscosity should be discussed in detail for students to understand viscous flow. Students can be shown different objects and have them placed in different fluids to sense the effects of more or less viscous fluids using the same objects. This demonstration or lab should also use particles of different sizes so students can actually see the effects of the Reynolds's number as the smaller particles will fall more slowly in the fluid or even become trapped in the fluid. An extension of this can be to have students look at pond scum under a microscope with a discussion that the movement of the microscopic organisms is also magnified (they are not moving as fast as you think they are because of the magnification factor). They can see that when objects stop using their flagella they quickly stop moving. This can then be used to discuss the swimmer in the pool as discussed earlier. This is an area where the discussion should also include ideas about gravity and the diminishing effects of gravity with objects of this size. This can generate an interesting discussion on knowing the objects may be stronger at this size, but they are also harder to propel if you need them to move.
A reminder of how elements react and bond with each other would be an important discussion to ensure they can understand the difference between inter, and intra-molecular bonds and forces. This may require a worksheet or short lecture to remind them of these things (it will have been 3 months since my students discussed these principles in class). Once students are reacquainted with this they can move into a discussion of self-assembly of products, and the need for people in industry to use self-assembly. This discussion can be about certain objects in nature that go through self-assembly and then lead students into the need for using nature's mechanisms to create objects in the nanoscale. This will conclude with a look at how objects even in the macroscale will self assemble. For more on this please look at section on activities.
Once students have completed a background secton on how physics effects objects of different size, this should generate a discussion of how and why we even build things at this scale. The class can develop a list of pros and cons for nanotechnology. This is a good time to share with them different ideas about the uses and applications of nanotechnology in medicines, in industry, and in consumer products. This will lead students to their culminating project and activity. Students will research one product of medical use of these materials and report about how it was developed and why, what its use and application is, and if there are any harmful or potentially harmful properties about these applications. The conclusion of their project should be a short piece of persuasion either for or against further research into nanotechnology.
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