reword drill bit choice section

[challenge-bot] / curriculum / challenge-bot.scm

diff --git a/curriculum/challenge-bot.scm b/curriculum/challenge-bot.scm
index 3aadc8d2596a71d744053faca63326131bd2f3ab..e1e942240690b0738beb4618ebf61dd95b584441 100644 (file)
--- a/curriculum/challenge-bot.scm
+++ b/curriculum/challenge-bot.scm
@@ -5,6 +5,7 @@
  :title [challenge-bot]
  (chapter
   :title [mechanical]
+  (p [let's build your robot!])
   (section
    :title [arduino to deck]
    (p [let's attach the arduino to the deck.])
@@ -21,23 +22,29 @@
               (item [alan wrench])
               (item [wood block])
               (item [arduino])
-              (item [#6-32x3/8\", four of them]))]))
+              (item [#6-32x3/8\", four of them])
+              (item [robot deck, the white thing with a grid of holes1]))]))
    (subsection
     :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