As kids put together our skill-building sun puzzles, they boost addition fluency with three addends—in a concrete, visual way! Each self-correcting puzzle features a number from 4 to 20, plus 5 equation pieces that each show a three-addend addition problem. Kids just match the number in the sun’s center to the corresponding equations—developing addition fluency with instant reinforcement! Set includes 17 puzzles divided into 4 skill levels that gradually progress in difficulty