A Geometry Shop Class
(Labor Day weekend, 1998)


Concentric hierarchy shapes for classroom demonstrations


Used compass and ruler to define 4" prime vector for tetrahedron, cube etc. Elmers & glue gun to hold edges, cloth tape applied when dry.

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Because of the thickness of the bookbinder material (28 ply), Russ incorporated thickness into dimensions of cube faces, so the gluing of adjacent sides might be flush, making for a stronger box with an internal volume having face-diagonals of 4". Other shapes took beads of hot glue along the creases (no attempt to bevel or mitre edges), followed with a tape covering.

We use red lentils (actually orange -- goes well with black tape) for pouring from one shape to another, to demonstrate volumetric relationships (one face left "open" on each shape). Working on pouring technique (might need a funnel).

We decided the rhombic triacontahedron was too precise and complicated to get out of the thick 28-ply so returned to Art Media on First Day for some thinner paperboard (also picked up more roles of cloth tape).

Helps to slightly bend 28-ply stuff apart with each stroke of the Xacto blade. We used a large paper cutter at Kinko's (protected slider cut, not one of those old cleaver-style models, which have been fazed out for safety reasons) to do long strips for the rhombic triaconta, leaving only slant-cuts for the Xacto:

------------------------------------------------  <-- Kinko's
 /    /    /    /    /    /    /    /    /    /   }
/    /    /    /    /    /    /    /    /    /    }
------------------------------------------------  <-- Kinko's

Shapes made (over Labor Day weekend):

Tetrahedron                 1
Cube                        3
Octahedron                  4
Rhombic Triacontahedron     5*
Rhombic Dodecahedron        6
Icosahedron                18.51+
Cuboctahedron              20

* given upper limits on precision associated with these construction
methods, there's no easy way to differentiate the E-module from the 
T-module RT, so we'll say this is the T-mod one, with volume 5 
precisely.  We might be off by a lentil or two.
I have presentations shaping up in Philadelphia, DC and New York in early November but haven't decided if I want to try lugging these shapes in my hand-carry or checked. I am hopeful that local centers will by then have similar props on hand for public domain sharing.

Oregon Curriculum Network



Office Depot
Glue Gun     $5.79
Knife.Xacto  $2.49 x 2
3M Tape      $1.49 x 2
Blade,#11    $4.79
Glue All       .48
Stanley Glue $2.69
Compass      $4.59
Ruler.Metal  $3.99
Ruler.Metal  $2.99

Art Media
28 Ply Recycled 32x40    $4.50
Rotex 3/4" Tape (black)  $1.39

Fred Meyer
Red lentils              $3.83

* not counting rhombic triaconta paper, didn't use the 3M tape, 
had to get 3 more roles of the black stuff.

For background reading:

For a wealth of hands-on science and math projects using everyday materials, more inexpensive (and safer) than the above, check out the TOPS Learning Systems website and materials.

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