University of Texas at Austin: Thomas Dillig's "Operational Semantics I"
Read these slides. While there are several forms of language semantics (axiomatic, denotational, and operational), we will focus on operational semantics in this course. Make sure that you understand the difference between eager versus lazy evaluation, and call-by-name vs call-by-value.
Click http://web.archive.org/web/20160726194639/http://www.cs.utexas.edu/~tdillig/cs345H/lecture7-6up.pdf link to open resource.