diff --git a/collects/teachpack/htdp/arrow-gui.ss b/collects/teachpack/htdp/arrow-gui.rkt similarity index 100% rename from collects/teachpack/htdp/arrow-gui.ss rename to collects/teachpack/htdp/arrow-gui.rkt diff --git a/collects/teachpack/htdp/arrow.ss b/collects/teachpack/htdp/arrow.rkt similarity index 100% rename from collects/teachpack/htdp/arrow.ss rename to collects/teachpack/htdp/arrow.rkt diff --git a/collects/teachpack/htdp/convert.ss b/collects/teachpack/htdp/convert.rkt similarity index 100% rename from collects/teachpack/htdp/convert.ss rename to collects/teachpack/htdp/convert.rkt diff --git a/collects/teachpack/htdp/dir.ss b/collects/teachpack/htdp/dir.rkt similarity index 100% rename from collects/teachpack/htdp/dir.ss rename to collects/teachpack/htdp/dir.rkt diff --git a/collects/teachpack/htdp/docs.ss b/collects/teachpack/htdp/docs.rkt similarity index 100% rename from collects/teachpack/htdp/docs.ss rename to collects/teachpack/htdp/docs.rkt diff --git a/collects/teachpack/htdp/draw.ss b/collects/teachpack/htdp/draw.rkt similarity index 100% rename from collects/teachpack/htdp/draw.ss rename to collects/teachpack/htdp/draw.rkt diff --git a/collects/teachpack/htdp/elevator.ss b/collects/teachpack/htdp/elevator.rkt similarity index 100% rename from collects/teachpack/htdp/elevator.ss rename to collects/teachpack/htdp/elevator.rkt diff --git a/collects/teachpack/htdp/graphing.ss b/collects/teachpack/htdp/graphing.rkt similarity index 100% rename from collects/teachpack/htdp/graphing.ss rename to collects/teachpack/htdp/graphing.rkt diff --git a/collects/teachpack/htdp/guess-gui.ss b/collects/teachpack/htdp/guess-gui.rkt similarity index 100% rename from collects/teachpack/htdp/guess-gui.ss rename to collects/teachpack/htdp/guess-gui.rkt diff --git a/collects/teachpack/htdp/guess.ss b/collects/teachpack/htdp/guess.rkt similarity index 100% rename from collects/teachpack/htdp/guess.ss rename to collects/teachpack/htdp/guess.rkt diff --git a/collects/teachpack/htdp/gui.ss b/collects/teachpack/htdp/gui.rkt similarity index 100% rename from collects/teachpack/htdp/gui.ss rename to collects/teachpack/htdp/gui.rkt diff --git a/collects/teachpack/htdp/hangman.ss b/collects/teachpack/htdp/hangman.rkt similarity index 100% rename from collects/teachpack/htdp/hangman.ss rename to collects/teachpack/htdp/hangman.rkt diff --git a/collects/teachpack/htdp/image.ss b/collects/teachpack/htdp/image.rkt similarity index 100% rename from collects/teachpack/htdp/image.ss rename to collects/teachpack/htdp/image.rkt diff --git a/collects/teachpack/htdp/lkup-gui.ss b/collects/teachpack/htdp/lkup-gui.rkt similarity index 100% rename from collects/teachpack/htdp/lkup-gui.ss rename to collects/teachpack/htdp/lkup-gui.rkt diff --git a/collects/teachpack/htdp/master.ss b/collects/teachpack/htdp/master.rkt similarity index 100% rename from collects/teachpack/htdp/master.ss rename to collects/teachpack/htdp/master.rkt diff --git a/collects/teachpack/htdp/matrix.ss b/collects/teachpack/htdp/matrix.rkt similarity index 100% rename from collects/teachpack/htdp/matrix.ss rename to collects/teachpack/htdp/matrix.rkt diff --git a/collects/teachpack/htdp/servlet.ss b/collects/teachpack/htdp/servlet.rkt similarity index 100% rename from collects/teachpack/htdp/servlet.ss rename to collects/teachpack/htdp/servlet.rkt diff --git a/collects/teachpack/htdp/servlet2.ss b/collects/teachpack/htdp/servlet2.rkt similarity index 100% rename from collects/teachpack/htdp/servlet2.ss rename to collects/teachpack/htdp/servlet2.rkt diff --git a/collects/teachpack/htdp/show-queen.ss b/collects/teachpack/htdp/show-queen.rkt similarity index 100% rename from collects/teachpack/htdp/show-queen.ss rename to collects/teachpack/htdp/show-queen.rkt diff --git a/collects/teachpack/htdp/testing.ss b/collects/teachpack/htdp/testing.rkt similarity index 100% rename from collects/teachpack/htdp/testing.ss rename to collects/teachpack/htdp/testing.rkt diff --git a/collects/teachpack/htdp/world.ss b/collects/teachpack/htdp/world.rkt similarity index 100% rename from collects/teachpack/htdp/world.ss rename to collects/teachpack/htdp/world.rkt