diff --git a/.DS_Store b/.DS_Store
index 2afc5c5..d0937e9 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/unit00_introduction/unit01_introduction.pptx b/unit00_introduction/unit01_introduction.pptx
index 62b98be..92cc766 100644
Binary files a/unit00_introduction/unit01_introduction.pptx and b/unit00_introduction/unit01_introduction.pptx differ
diff --git a/unit01_cipher_fundamentals/.DS_Store b/unit01_cipher_fundamentals/.DS_Store
index fe11a3b..18467d3 100644
Binary files a/unit01_cipher_fundamentals/.DS_Store and b/unit01_cipher_fundamentals/.DS_Store differ
diff --git a/unit02_symmetric/.DS_Store b/unit02_symmetric/.DS_Store
index 3bad1f4..2c56e59 100644
Binary files a/unit02_symmetric/.DS_Store and b/unit02_symmetric/.DS_Store differ
diff --git a/unit10_services/lecture/~$unit09_host_services2.pptx b/unit02_symmetric/lecture/~$chapter02_secret.pptx
similarity index 100%
rename from unit10_services/lecture/~$unit09_host_services2.pptx
rename to unit02_symmetric/lecture/~$chapter02_secret.pptx
diff --git a/unit04_public_key/.DS_Store b/unit04_public_key/.DS_Store
index 94e64be..c106c29 100644
Binary files a/unit04_public_key/.DS_Store and b/unit04_public_key/.DS_Store differ
diff --git a/unit08_blockchain/.DS_Store b/unit08_blockchain/.DS_Store
index 903cfb5..45fb92d 100644
Binary files a/unit08_blockchain/.DS_Store and b/unit08_blockchain/.DS_Store differ
diff --git a/unit09_future/lecture/unit09_next_gen.key b/unit09_future/lecture/unit09_next_gen.key
index 22d922f..17425c6 100755
Binary files a/unit09_future/lecture/unit09_next_gen.key and b/unit09_future/lecture/unit09_next_gen.key differ
diff --git a/unit10_services/.DS_Store b/unit10_services/.DS_Store
index 0f54506..a679f56 100644
Binary files a/unit10_services/.DS_Store and b/unit10_services/.DS_Store differ
diff --git a/unit10_services/lecture/unit09_host_services2.pptx b/unit10_services/lecture/unit09_host_services2.pptx
index e96f233..dcdad40 100644
Binary files a/unit10_services/lecture/unit09_host_services2.pptx and b/unit10_services/lecture/unit09_host_services2.pptx differ
diff --git a/z_assessments/.DS_Store b/z_assessments/.DS_Store
index 93a1567..56d3685 100644
Binary files a/z_assessments/.DS_Store and b/z_assessments/.DS_Store differ
diff --git a/z_assessments/coursework/.DS_Store b/z_assessments/coursework/.DS_Store
index 68c06ca..b105248 100644
Binary files a/z_assessments/coursework/.DS_Store and b/z_assessments/coursework/.DS_Store differ