X-Git-Url: http://challenge-bot.com/repos/?a=blobdiff_plain;f=curriculum%2Fchallenge-bot.scm;h=72de0cff48333284c86fa70aa1880daedf92f4c5;hb=27547a790e79d26818b4d4611d23571c02384af4;hp=7b6eef3f0bd507aa186e67bb0a9bfed885e77930;hpb=d08737561143e6976048bb82189bbec63278458b;p=challenge-bot

diff --git a/curriculum/challenge-bot.scm b/curriculum/challenge-bot.scm
index 7b6eef3..72de0cf 100644
--- a/curriculum/challenge-bot.scm
+++ b/curriculum/challenge-bot.scm
@@ -28,22 +28,35 @@
     :title [first hole]
     (subsubsection
      :title [choosing drill bit]
-     (p [choosing the right drill bit depends on what job you are doing.
-                  right now, we are making holes for screws to hold the
-                  arduino to the deck.
-                  this means the hole needs to be big enough for the
-                  screw body to fit through.
-                  we want the screw to stay put once it's in place.
-                  we also want the drill bit to be smaller than the
-                  diameter of the thread.
-                  the screw was chosen so that the hole on the arduino
-                  was bigger than the body and smaller than the thread.
-                  we will choose the biggest drill bit that fits through
-                  the hole on the arduino.])
+     (p [the arduino comes with holes in it already, so we will make
+             some choices around those holes.
+             choosing the right drill bit depends on what job you are
+             doing.
+             right now, we are making holes for screws to hold the
+             arduino to the deck.
+             there are two constraints between the hole and screw.
+             each hole needs to be big enough for the screw body to fit
+             through it.
+             the holes also need to be smaller than the screw's thread.
+             since there are holes on the arduino already, the screw was
+             chosen to match it.
+             the screw was chosen so that the hole on the arduino was
+             bigger than the screw body and smaller than its thread.
+             we will choose the biggest drill bit that fits through the
+             hole on the arduino, then use that to drill holes in the
+             deck.])
      (p [here's a cross section of a screw in the deck]
         (figure :legend "screw cross section"
                 (image :file
-                       "arduino-to-deck/screw-cross-section.png"))))
+                       "arduino-to-deck/screw-cross-section.png")))
+     (p [check
+         ,(itemize
+           (item
+            [what would happen if the drill bit were larger than the
+                  screw thread?])
+           (item
+            [what would happen if the drill bit were smaller than the
+                  screw body?]))]))
     (subsubsection
      :title [inserting drill bit]
      (p (figure :legend "arduino to deck / insert bit"