Sift the flour, baking powder, baking soda, salt, and cinnamon together in a large bowl. Stir with your hand to be sure the ingredients are combined. In a 2-cup glass measure, combine the milk, eggs, and melted butter. Make a well in the middle of the dry mixture, pour the wet mixture into the well, and stir until just combined. There will be some lumps but don’t overmix the batter! Add the strawberries and sugar and stir gently to combine.