diff --git a/docs/lessons.md b/docs/lessons.md
index f59dbb51..58790875 100644
--- a/docs/lessons.md
+++ b/docs/lessons.md
@@ -59,6 +59,7 @@
 
 ## Science
 * [Charting](/lessons/charting), measure and chart acceleration
+* [Seismograph](/lessons/seismograph), create a seismograph with household items
 
 ## Advanced
 * [Prank WiFi](/lessons/prank-wifi), create fake WiFi to trick your friends
diff --git a/docs/lessons/seismograph6.png b/docs/lessons/seismograph6.png
deleted file mode 100644
index b26b8e22..00000000
Binary files a/docs/lessons/seismograph6.png and /dev/null differ
diff --git a/docs/lessons/seismograph8.png b/docs/lessons/seismograph8.png
deleted file mode 100644
index 1611a3ed..00000000
Binary files a/docs/lessons/seismograph8.png and /dev/null differ