How to Make It
Squeeze lemon halves to equal 1 cup juice. Reserve juice and 4 squeezed lemon halves.
Stir together sugar and 1 cup of the water in a small saucepan over medium-high, and cook, stirring often, just until sugar dissolves. Remove from heat, and cool 10 minutes.
Pour sugar syrup into a large pitcher. Add 4 cups ice, and stir until ice is mostly melted, about 1 minute. Add reserved lemon juice and remaining 2 cups water; stir to combine. Chill lemonade until ready to serve. Place 1 squeezed lemon half and ice in each of 4 tall glasses; pour in lemonade.