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+As a recap, we've talked about how numbers work, how characters work, how characters are combined into text via lexers and parsers, and how numbers and text are combined via operators in custom classes:
+
+```
+Numbers ------------------------> Operators -> ?
+Characters --(Lexers/Parsers) --> Operators -> ?
+```
+
+Today's homework is to think about how to design classes, or what the industry calls "object-oriented design."  You have to be careful to minimize complexity when designing public interfaces and APIs to your code, otherwise this happens:
+
+https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpriseEdition/blob/uinverse/src/main/java/com/seriouscompany/business/java/fizzbuzz/packagenamingpackage/impl/loop/LoopCondition.java
+
+Remember fizzbuzz?  This is a satirical version built using every object-oriented pattern in the book.  There is an actual book on the subject, which is widely respected throughout the industry, and in some cases misused to overcomplicate code:
+
+https://en.wikipedia.org/wiki/Design_Patterns
+
+The assignment for today is to think about some everyday thing you interact with, such as an elevator, a pet, or anything which has tangible and measurable *inputs* and *outputs*.  There are three files to look at in the `simulation` directory in this repository:
+
+* SimulationRunner: a program to run simulation classes.
+* Simulation: the interface definition for a simulation.
+* HotdogSimulation: a class simulating a hot dog.
+
+Design two versions of this object with the following shared criteria:
+
+* Define the start, stop, tick, get_uses, and use methods.
+* Ensure that the object expires when a reasonable number of ticks have passed.
+
+One version of the object should be very simple, such as the hot dog example.
+
+The other version of the object should be overly complicated, with verbs such as `weigh` to get its mass, `mood` to get its mood, `price_tag` to have it return its estimated value, and `go_to_moon` to send the object to the moon (in the case of the pet, it would probably explode and `use()` should return `False`).  Try to define at least 20 different verbs you could use on the object, with associated instance variables to track its state so the verbs interact correctly.  For example, a `throw` verb on a hot dog should reduce its mass, because some of its condiments will end up on the target.
+
+Although it would be preferred to create a Python file that can be run under the simulator, a text specification is also acceptable.  The important thing is for the object to have a consistent model of its state which accurately represents what would happen in real life when methods (verbs) are applied to it.
+