small cob projects for kids

In the fall, we will be homeschooling our children, and I am the parent who will be teaching the Biblical studies portion of our curriculum.  When we discuss the period in which the Pharoah required the Jewish slaves to make brick without straw, I thought it might be fun to try a manageable "cob building" project with my kids to show them the significance of straw to the process.  I've never worked with cob before, so I would like to keep it pretty simple. Any suggestions?