Construction Techniques
This Technic Primer [1] is a resource form Carnegie Mellon Univerisity's Robotics Academy (http://www.education.rec.ri.cmu.edu/ [2]) Robotics Engineering Vol. 1 product (http://www.education.rec.ri.cmu.edu/content/lego/curriculum/rev1_index.htm [3]).
Joining Pieces (examples 1 thru 4)
 Student can construct 4 assemblies using different friction pegs and beams
Stationary Axles (examples 1 and 2)
 Students can construct 2 assemblies using axles as structural elements
Optional : Reinforcing Structures and Size Scale
 Student will not use these techniques soon or often – may be overkill at this point
Optional : Pulleys, Cam Rods and Axis of Rotation
 Student will not use these techniques soon or often – may be overkill at this point
Gears

Assemble Gear Train (steps 1 thru 4 in primer)
 Add 3 bushings to secure gears (similar to Photo 1_1 [4])
 Note ease of motion

Alter assembly to use 3 nonfriction pegs (tan colored) instead of axles
 Note ease of motion

Alter assembly to use 3 friction pegs (blue colored)
 Note difficulty of motion
Structural Building Challenge
Use the Building Challenges PPT [5] to give students more insight and practice on techniques for building sturdy and efficient structures with the NXT kit.
Slide 1
In order to extend a straight beam, a minimum of two pegs must be used
 The further apart the pegs are, the stronger the connection, but the shorter the resulting extended beam
Slide 2
Triangles make very sturdy, strong structures – even when only attached by one peg
Rectangles (or squares) are not sturdy when only attached by one peg – they readily morph into parallelograms
 To make rectangles sturdy, at least one corner must be locked at a rightangle – this will inhibit the other corners from moving too
 The more corners locked, the stronger the rectangle
Slide 3
To make rectangles sturdy, at least one corner must be locked at a rightangle – this will inhibit the other corners from moving too
 The more corners locked, the stronger the rectangle
 Corners can be locked with angled beams and multiple pegs or by creating a triangle in the corner with another beam
A flat rectangle (or square) presents other challenge
 Locking these corners will take many pieces unless….
 This snapbeam part creates a very fast, efficient and effective means of accomplishing this
 If students try the snapbeam first, have them also try to solve this without using the snapbeam so they appreciate the elegance of this solution
The minibridge challenge gives students a chance to put this new learning into practice
 Have students build their bridges

Encourage then to not simply create a plank bridge (as in the example photo) but also think about how to use triangles to make it stronger
 Creating triangles on the side of the bridge where one side is two beams on the bridge deck (that will bow together when weight is added) and the other two sides are additional beams connected above the bridge deck, will increase the load capacity of the bridge deck
 Test the student bridges by incrementally adding weight
 Discuss why some bridges to better than others
 Examine the point of failure on bridges that collapse early
 Discuss ways these could be improved
Slide 4
This challenge is all about build longandstrong (slide 1)
 The structural building learning (slides 2,3) can be assessed in the Faraday Golf Challenge in the NXT First Build lesson
As an extended challenge, have students place the brick/battery between the bridge and motor/dude for an additional load on the bridge
Slide 5
Print out this grading sheet for students
Slide 6
Note: the kit used in this example had 6 straight snapbeam more than the standard 9797 kit