1. A child seeing a zebra for the first time and calling it a horse. The child assimilates this information into her schema for a horse. When the child accommodates information, she takes into consideration the different properties of a zebra compared to a horse, perhaps calling a zebra a horse with stripes. When she eventually learns the name of zebra, she has accommodated this information.
2. A mental representation, or schema of a certain group of people (a racist schema) -- your whole life you grew up with those around you just adding more and more information to that schema that made sense to you (assimilation) -- you only notice information that fits your schema (assimilation) and confirms it -- then you get to college and actually meet people from that group and realize what you have learned from real interactions requires a radical reorganization of your schema regarding that group (accommodation). Your new schema is completely different, not just full of additional information
3. Assimilation is like adding air into a balloon. You just keep blowing it up. It gets bigger and bigger. For example, a two year old's schema of a tree is "green and big with bark" -- over time the child adds information (some trees lose their leaves, some trees have names, we use a tree at Christmas, etc.) - Your balloon just gets full of more information that fits neatly with what you know and adds onto it.
Accommodation is when you have to turn your round balloon into the shape of a poodle. This new balloon "animal" is a radical shift in your schema (or balloon shape). The tree example works well where we live so I go with that, but you can invent your own. Now that they are in college in the redwood forest, we have conceptualization (schema) of trees as a source of political warfare, a commodity, a source of income for some people, we know that people sit and live in trees to save them; in