diff --git a/w20-triangle-centers/triangle-centers-notes.pdf b/w20-triangle-centers/triangle-centers-notes.pdf
new file mode 100644
index 0000000..71bff69
Binary files /dev/null and b/w20-triangle-centers/triangle-centers-notes.pdf differ
diff --git a/w20-triangle-centers/triangle-centers-notes.xopp b/w20-triangle-centers/triangle-centers-notes.xopp
new file mode 100644
index 0000000..28b582a
Binary files /dev/null and b/w20-triangle-centers/triangle-centers-notes.xopp differ
diff --git a/w20-triangle-centers/triangle-centers.pdf b/w20-triangle-centers/triangle-centers.pdf
deleted file mode 100644
index dded277..0000000
Binary files a/w20-triangle-centers/triangle-centers.pdf and /dev/null differ
diff --git a/w20-triangle-centers/triangle-centers.xopp b/w20-triangle-centers/triangle-centers.xopp
deleted file mode 100644
index e27ceae..0000000
Binary files a/w20-triangle-centers/triangle-centers.xopp and /dev/null differ
diff --git a/w20-triangle-centers/triangles-centers-lecture.xopp b/w20-triangle-centers/triangles-centers-lecture.xopp
new file mode 100644
index 0000000..f45378e
Binary files /dev/null and b/w20-triangle-centers/triangles-centers-lecture.xopp differ
diff --git a/w20-triangle-centers/triangles-centers-solutions.pdf b/w20-triangle-centers/triangles-centers-solutions.pdf
new file mode 100644
index 0000000..1f58e36
Binary files /dev/null and b/w20-triangle-centers/triangles-centers-solutions.pdf differ