Educational toy made in plastic versions. In the mid-1950s, more explicitly engineering-themed construction toys appeared, including plastic girders, columns, and panels that could be assembled into a model curtain wall skyscraper. Later, this Girder and Panel structural system was extended to a Hydro-Dynamic setup by adding pipes, valves, tanks, nozzles, and pumps to allow construction of model plumbing, HVAC, and chemical engineering systems like a simulated distillation column. Other extensions of the system supported suburban-style housing developments (Build-A-Home), or monorail transportation systems (Skyrail). The building toy Lego was originally developed by Ole Kirk Christiansen in Billund, Denmark, in the 1930s. The name
Lego looking at different aspects of the construction toy. The first was "The Ultimate Lego Book", published in 1999. More recently, in 2009, the same publisher produced "The LEGO Book", which was sold within a slipcase along with "Standing Small: A celebration of 30 years of the LEGO minifigure", a smaller book focused on the minifigure. In 2012, a revised edition was published. Also in 2009, DK also published books on Lego Star Wars and a range of Lego-based sticker books. Although no longer being published in the United States by Scholastic, books covering events in the Bionicle storyline are written