Figure 1. Beth Shalom Synagogue, Elkins Park, Pennsylvania, Frank Lloyd Wright, 1954-1959
In 1876, Frank Lloyd Wright’s mother attended the Centennial Exposition in Philadelphia and visited the Kindergarten exhibit where she saw a Froebel Kindergarten Chest of Toys., Mrs. Wright was certain her 9-year old son, Frank, would one day become an architect, so she later purchased a Froebel Chest that included wooden blocks in varied geometric shapes, and a set of toothpicks and peas that invited children to assemble 3-dimensional structures. Decades later, Wright said that he had played with the cube, the sphere, and the triangle stating that “All are in my fingers to this day…” Throughout his career, Wright used various geometric motifs, but the diagonal, arguably, had the greatest impact on other architects during his lifetime and after. A building project symbolic of Wright’s lifelong engagement with the diagonal is Beth Shalom synagogue outside of Philadelphia [fig.1].
The corrugated, wire-glass tetrahedral roof sits on a concrete base whose projecting bat-like ears redirect the structural loads downward from three, tripod-shaped, aluminum-faced steel girders.
The design of Beth Shalom is based on one of Wright’s unbuilt earlier schemes called the Steel Cathedral. Author Joseph M. Siry notes “…the crystalline metaphor had been a favorite motif of the German expressionists, whose projects of the 1920s may have inspired both the Steel Cathedral and Beth Shalom.”
 The teaching aid was developed between 1838-1840.
 The Centennial Exposition commemorated the 100th birthday of the signing of the Declaration of Independence. Ten million visitors travelled to the event that summer from the U.S. and abroad. Eight American glass manufacturers exhibited their products at the Exhibition, marking the start of the very popular Brilliant period in cut glass manufacturing. Complex geometrical incisions characterize this era of cut glass.
 Born, Frank Lincoln Wright in Richland Center, WI, 1867-1959.
 Mrs. Wright (1838/39—1923), actually purchased the chest upon retuning to the family home in Weymouth, MA.
 The peas would be soaked in water to soften them adequately to receive the toothpicks.
 A detailed history of the Froebel phenomenon is described in Norman Brosterman’s Inventing Kindergarten, Harry N. Abrams, Inc, 1977, and in Jeanne Spielman Rubin’s Intimate Triangle: Architecture of Crystals, Frank Lloyd Wright, and the Froebel Kindergarten, Polycrystal Book Service, 2002
 One noteworthy example is U.S. architect, Bruce Goff, whose work is mentioned and illustrated later in this note.
 Siry, Joseph M., Beth Shalom Synagogue: Frank Lloyd Wright and Modern Religious Architecture, University of Chicago Press, 2012. The synagogue still stands in Elkins Park, PA.
 An inner layer of blue plastic had been planned but was not executed.
 One can imagine this arrangement made from moist peas and tooth picks on Wright’s Froebel kindergarten table.
 Designed between 1926 and 1929
 Siry, Joseph M.