Children ages 3 and up can experience a nature-inspired, tactile building experience indoors and outdoors with Big Branch Block Builders 125-piece set. Real branches in various lengths feature notched sides for perpendicularly stacked builds. Special parts create window frame and roof details. The unrefined wood and real branch material wears over time, revealing cause and effect behaviors and natural evolution to children. 10 double-sided concept cards enhance hands-on building activities by providing creative inspiration and real-life examples. Additional loose parts not included. Shortest branch measures 2.25" , longest branch measures 13.75" .