I'm having difficulty trying to draw up an ER diagram based on a particular homework problem in my textbook for a college level database management course. We have just started learning about all of the basics of an ER model such as the degree, cardinality, entities, attributes, and relationships. The problem I'm having difficulty with is as follows: A piano manufacturer wants to keep track of all the pianos it makes individually. Each piano has an identifying serial number and a manufacturing completion date. Each instrument represents exactly one piano model, all of which have an identification number and a name. In addition, the company wants to maintain information about the designer of the model. Over time, the company often manufacturers thousands of pianos of a certain model, and the model design is specified before any single piano exists. What I've deduced from this problem is that the entities are piano, model, and possbly designer? The attributes for piano are serial number and completion date. The attributes for model are ID number and name. I don't have any attributes for desginer, and our professor told us not to make any up if they aren't specified. For this problem, is PIANO a weak entity since it says the model is designed before any PIANO exists implying it has to have model as its identifying owner? Would DESIGNER be an entity as well? Where would it be placed? I've figured out a cardinality between PIANO and MODEL of exactly one and a cardinality of MODEL to PIANO of 0, 1, or many. I cant determine any cardinalities between DESIGNER and the other entities based on the problem. Any assistance with this would be greatly appreciated. I would not consider my professor the best, as I know many of the students seemed to be confused about properly drawing the diagrams. The professor mentioned that if a diagram is drawn representing a binary or ternary relationship when it could have been represented with an associaitve entity, points will be subtracted. This is what I have so far, and it doesn't feel right. Edit: For the problem, the degree and cardinalities of the relationship must be explained in addition to the a diagram of the relationship.