1. Model Relationships Read the relationships.
Write the relationship sentences for this E-R diagram.
ORDER
number
type
ITEM
number
description
issued for
bought
via
stored in
originated by
the
originator of
the
repository
for
CUSTOMER
first name
last name
WAREHOUSE id
address

2. Model Relationships – Solution
Each ORDER must be issued for one or more ITEMs.
Each ITEM may be bought via one or more ORDERs.
Each ORDER must be originated by one and only one CUSTOMER.
Each CUSTOMER may be the originator of one or more ORDERs.
Each ITEM must be stored in one and only one WAREHOUSE.
Each WAREHOUSE may be the repository for one or more ITEMs.

3. Modeling Exercise Draw an Entity-Relationship Diagram.
Draw an Entity-Relationship diagram to represent the following:
a Each EMPLOYEE must be assigned to one and only DEPARTMENT.
b Each DEPARTMENT may be responsible for one or more EMPLOYEEs.
c Each EMPLOYEE may be assigned to one or more ACTIVITIES.
d Each ACTIVITY may be performed by one or more EMPLOYEEs.

4. Modeling Exercise Solution
DEPARTMENT
EMPLOYEE
assigned to
responsible
for
assigned to
performed by
ACTIVITY

5. Discussion
Pair students and have them brainstorm on the following questions:
What are all the categories to which you belong or would like to?
Be creative.
Use all applicable labels that apply (and some that don't!) i.e. student, child, young adult, city, state, clerk, athlete, musician, sci-fi reader, prankster, etc.
Have students write 5 minutes in their journal on the question "How can you scale down your understanding of 'school' to entities?
What categories have significance? (this could be a loaded question!)
Facilitate discussion of journal responses.