Simplify the following text for a Grade 14 native English-speaking person.
Original: Rather than returning to bureaucratic rule after dismissing the national assembly , Frederick William promulgated a new constitution that created a parliament with two chambers , an aristocratic upper house and an elected lower house .
Simplified: When he had dismissed the national assembly , Frederick William decided to have a constitution with a parliament with two chambers , an aristocratic upper house and an elected lower house .