Teacher Answer Guide
  1. Briefly describe the role of the magnet in the MRI system and its effect on chicken eggs for taking MRI pictures.

    For a detailed explanation on how the MRI works, please see the MRI introduction for high school students in the Chickscope tutorial. A simpler explanation is in the middle school students introduction to MRI. A key thing to look for in your students' answers is if they understand the importance of magnetism to the workings of MRI. For example, how the water molecule is a kind of magnet, and there are many water molecules in chicken eggs.

  2. Why is the MR image black and white?

    It will be good to go over this issue during your MRI introduction in the classroom. This question may be asked by your students to you as well. Please see the sample Chickscope questions and answers in the tutorial.

    Actually, the MR image has no "colors" at all - it is a radio signal. But in order to make it visible, the computer artificially colors it. Since a single image conveys only one value at each point, we choose to assign that value to "brightness".

    It could also be assigned to a color, however, to make a "pseudo-color image". If you have the right software in your computer, you can change the colors to suit yourself.

    The black and white choice has other bases, too. MRI is often done along with X-rays in a hospital radiology department. The doctors are used to looking at black and white x-rays, so it was natural to do MRI in the same way.

  3. Why are MR images usually acquired as "slices"?

    Students should be encouraged to go through the "Why Slices?" page to get an introduction to slices on the 48-hour chick embryo. MRI scans focus their magnetic field onto a thin layer of the embryo and collect a series of pictures in slices.

  4. Identify and annotate the eye structure of the developing chick on any two images from the set of five images you have for this unit.

    Before having your students start on the eye measurement activity, please encourage them to go through the sample annotated MR images in the Chickscope tutorial. This will get them familiar with the developmental anatomy of the chick as they work with MRI data.

  5. Plot a graph of the diameter of eye vs. the age (in days) of the chick using the five images. Does the size of the eye increase from day to day? If not, why not? Is it difficult to get a good measurement of the eye? Why or why not?

    A key thing to look for in your students' answers is if they are using MR images of the same scale. Check their field of view when evaluating their response. (See the Making a Montage section in the Instructions for NIH Image.)

  6. Based on your initial hypotheses and final conclusions, what have you learned about the "scientific method" from this unit? If you have formulated alternative hypotheses to explain unexpected results, please write them.

    Since the unit is attempting to introduce scientific inquiry to your students, it is important for students to have gone through the various steps outlined in the lesson. The MRI data they are working with will have irregularities and surprises, and so it is important to make them aware of the uncertainties in science.

  7. Bonus question (optional for middle school students) Which element present in the egg is most useful for taking MR images? Look up the Magnetic Resonance Periodic Table and find out the nuclear spin for this element.

    When you introduce the periodic table to your students, it may be good to share the Magnetic Resonance Periodic Table as well. The students should be able to easily find their way to the Hydrogen element.

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