EdX offers full support for this problem type.
Open response assessments (ORA), sometimes also called peer assessments, are a flexible assignment type in which learners answer questions that might not have definite answers. Learners submit text responses or short essays. You can also require learners to submit an image or other type of file to accompany their written responses.
After submitting their original responses, learners are guided through a series of assessment steps that can include a training step, peer assessment, self assessment, and staff assessment.