MFM Extensions

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Return to the MFM Challenge.

There are a number of potential approaches when presenting students with the MFM challnge. These will vary based on your educational objectives as well as the time and resources available to carry them out. This page presents some ideas and suggestions for varying the difficulty, time, and depth of the challenge to suit your needs and objectives.


Varying Challenge Difficulty


The students are provided with the conceptual information behind the MFM, full instructions and materials for building the pre-designed MFM, and the code to drive the MFM (see 'Build Instructions' below). They should be given enough time to build the device (possibly outside of class, it can be expected to take 3-4 hours). After construction is completed, students are given samples to analyze and asked to interpret the output from the device. The challenge here is simply the construction and usage of the device and the goal is mainly to demonstrate the ideas behind the MFM. This is recommended for younger audiences or in situations where the module needs to be run quickly and is mostly intended to convey concepts.


The students are provided with the conceptual information behind the MFM and instructions and materials for building the pre-designed MFM. Depending on their educational background and the goals of the instruction they may also be given the sample code to drive the MFM. The students will be asked to modify the existing design to resolve a finer resolution sample. When construction is finished they are given 3 samples of varying difficulty and asked to determine their contents using the device. The easiest sample should have a wide spacing between magnets, while the other two should have increasingly smaller gaps. The challenge lies in the students being able to modify the machine to study the increasing resolutions in the samples.


The students are presented only with the MFM conceptual information and asked to design and construct the device from scratch as in the main challenge. When they have completed the design and construction of their devices they should be given three samples of varying difficulty. Polarity of the magnets can also be introduced as a variable (see below). The challenge here is in the design itself, it is meant for inclusion within engineering curricula that wish to supplement with nanotechnology ideas and concepts. The activity is expected to be performed in small teams with students given 4-5 weeks to complete the task.

Varying Resolution Levels/Polarity

Challenge level can be adjusted by varying the resolution of the sample as is suggested in the Intermediate and Difficult challenge descriptions. The complexity of the magnet placement within the sample can also be varied. Resolution is at a maximum when the entire table is covered with blocks that could potentially hold magnets. Resolution is decreased as empty, intervening space is inserted between the magnet containing blocks. The more tightly packed the blocks are, the more precise the students' control over their machines needs to be in order to obtain valid readings. Descriptive images can be found below in Sample Construction. Polarity changes can also be included to add an increased level of difficulty to the challenge. Students will then need to add some type of sensor (probably a touch sensor) to detect which way the arm has been deflected from its equilibrium point.

Build Instructions

Full build instructions for the MFM platform are available here.

A sample video of its operation is available as well.

Source code for driving the platform with NXT-G is available here.

MFM Sample Construction

Low Resolution Sample

Low Resolution Sample

High Resolution Sample

High Resolution Sample

Magnet Placement within Lego

Hidden Magnet

Notes to Educators

Please assume that your students will find this page and all the design documents contained on it. It my be more productive for you to disclose its existence upfront and suggest that it be used for guidance and inspiration.

Students should be aware at the outset of the project of any challenge they need to perform to be successful. This includes any different levels of resolution and/or complexity in the magnet set up. Polarity reversal is also an important piece of information as students will need to design around this (the light sensor alone will not allow for determination of direction of deflection). Students should also be given some mechanism for testing their design as they build it. Testing and prototyping are critical parts of any engineering design process and any project neglecting this fact would do students an injustice. At the least they should have a few magnets available to use for testing.

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