diff --git a/lectures/lec22/em.ipynb b/lectures/lec20/em.ipynb
similarity index 100%
rename from lectures/lec22/em.ipynb
rename to lectures/lec20/em.ipynb
diff --git a/lectures/lec23/cluster.ipynb b/lectures/lec21/cluster.ipynb
similarity index 100%
rename from lectures/lec23/cluster.ipynb
rename to lectures/lec21/cluster.ipynb