diff --git a/bolt_checkin_notes.txt b/bolt_checkin_notes.txt
index c1b8ef3d81..2494f484b3 100644
--- a/bolt_checkin_notes.txt
+++ b/bolt_checkin_notes.txt
@@ -234,3 +234,15 @@ David  Oct 20 2008
 David  Oct 23 2008
     - Add callback mechanism for exercises and exercise sets
     - Default count for exercise sets is N, not 1
+    - Switch from JSON to PHP serialization
+        (NOTE: this requires cleaning out your DB)
+
+David  Oct 23 2008
+    - Change the info passed to/from exercise functions from
+         bunch of globals to a single global struct
+    - Change the arguments to exercise functions
+        to allow for a weight() arg
+
+    html/
+        inc/
+            bolt_ex.inc
diff --git a/html/inc/bolt_ex.inc b/html/inc/bolt_ex.inc
index 294daca346..30f4d1219b 100644
--- a/html/inc/bolt_ex.inc
+++ b/html/inc/bolt_ex.inc
@@ -18,27 +18,55 @@
 
 // Bolt exercise API
 
-$bolt_ex_mode = 0;
-$bolt_ex_index = 0;
-$bolt_ex_state = 0;
-$bolt_ex_score = 0;
-$bolt_ex_query_string = "";
+// The following is a global var accessed by exercise functions.
+//
+$bolt_ex = null;
+$bolt_ex->mode = 0;     // input: SHOW/SCORE/ANSWER
+$bolt_ex->index = 0;    // input: sequence of this exercise in file
+$bolt_ex->score = 0;    // input/output: cumulative score (if mode = SCORE)
+$bolt_ex->weight = 0;   // input/output: cumulative weight
+$bolt_ex->query_string = "";    // user's response (if SCORE or ANSWER)
 
-function exclusive_choice($choices) {
-    global $bolt_ex_mode;   // input
-    global $bolt_ex_index;  // input
-    global $bolt_ex_score;  // incremental output if SCORE
-    global $bolt_ex_query_string;
+class BoltWeight {
+    public $weight;
+    function __construct($weight) {
+        $this->weight = $weight;
+    }
+}
 
-    parse_str($bolt_ex_query_string);
+function weight($w) {
+    return new BoltWeight($w);
+}
 
-    switch ($bolt_ex_mode) {
+function exclusive_choice() {
+    global $bolt_ex;
+    $weight = 1;
+
+    $choices = array();
+    $args = func_get_args();
+    foreach ($args as $arg) {
+        if (is_string($arg)) {
+            $choices[] = $arg;
+        } else if (is_object($arg)) {
+            if (get_class($arg) == 'BoltWeight') {
+                $weight = $arg->weight;
+            } else {
+                "bad arg to exclusive_choice()";
+            }
+        } else {
+            "bad arg to exclusive_choice()";
+        }
+    }
+
+    parse_str($bolt_ex->query_string);
+
+    switch ($bolt_ex->mode) {
     case BOLT_MODE_SHOW:
         shuffle($choices);
         $i = 0;
         start_table();
         foreach ($choices as $choice) {
-            row2($choice, "<input name=q_$bolt_ex_index type=radio value=$i>");
+            row2($choice, "<input name=q_$bolt_ex->index type=radio value=$i>");
             $i++;
         }
         end_table();
@@ -46,18 +74,19 @@ function exclusive_choice($choices) {
     case BOLT_MODE_SCORE:
         $right_ans = $choices[0];
         shuffle($choices);
-        $key = "q_$bolt_ex_index";
+        $key = "q_$bolt_ex->index";
         if (isset($$key)) {
             $response = $$key;
             if ($choices[$response] == $right_ans) {
-                $bolt_ex_score += 1;
+                $bolt_ex->score += 1;
             }
         }
+        $bolt_ex->weight += $weight;
         break;
     case BOLT_MODE_ANSWER:
         $right_ans = $choices[0];
         shuffle($choices);
-        $key = "q_$bolt_ex_index";
+        $key = "q_$bolt_ex->index";
         if (isset($$key)) {
             $response = $$key;
         } else {
@@ -84,25 +113,39 @@ function exclusive_choice($choices) {
         end_table();
         break;
     }
-    $bolt_ex_index++;
+    $bolt_ex->index++;
 }
 
-function inclusive_choice($choices) {
-    global $bolt_ex_mode;   // input
-    global $bolt_ex_index;  // input
-    global $bolt_ex_score;  // incremental output if SCORE
-    global $bolt_ex_query_string;
+function inclusive_choice() {
+    global $bolt_ex;
+    $weight = 1;
 
-    parse_str($bolt_ex_query_string);
+    $choices = array();
+    $args = func_get_args();
+    foreach ($args as $arg) {
+        if (is_array($arg)) {
+            $choices[] = $arg;
+        } else if (is_object($arg)) {
+            if (get_class($arg) == 'BoltWeight') {
+                $weight = $arg->weight;
+            } else {
+                "bad arg to inclusive_choice()";
+            }
+        } else {
+            "bad arg to inclusive_choice()";
+        }
+    }
 
-    switch ($bolt_ex_mode) {
+    parse_str($bolt_ex->query_string);
+
+    switch ($bolt_ex->mode) {
     case BOLT_MODE_SHOW:
         shuffle($choices);
         $i = 0;
         start_table();
         foreach ($choices as $choice) {
             $c = $choice[0];
-            row2("<input name=q_".$bolt_ex_index."_$i type=checkbox>", $c);
+            row2("<input name=q_".$bolt_ex->index."_$i type=checkbox>", $c);
             $i++;
         }
         end_table();
@@ -113,14 +156,15 @@ function inclusive_choice($choices) {
         $score = 0;
         shuffle($choices);
         foreach ($choices as $choice) {
-            $key = "q_".$bolt_ex_index."_$i";
+            $key = "q_".$bolt_ex->index."_$i";
             $response = isset($$key);
             $r = $choice[1];
             $correct = ($r && $response) || (!$r && !$response);
             if ($correct) $score += 1./$n;
             $i++;
         }
-        $bolt_ex_score += $score;
+        $bolt_ex->score += $score;
+        $bolt_ex->weight += $weight;
         break;
     case BOLT_MODE_ANSWER:
         $i = 0;
@@ -130,7 +174,7 @@ function inclusive_choice($choices) {
         table_header("Choice", "Correct?", "Your answer");
         foreach ($choices as $choice) {
             $c = $choice[0];
-            $key = "q_".$bolt_ex_index."_$i";
+            $key = "q_".$bolt_ex->index."_$i";
             $response = isset($$key);
             $r = $choice[1];
             $correct = ($r && $response) || (!$r && !$response);
@@ -143,18 +187,15 @@ function inclusive_choice($choices) {
         end_table();
         break;
     }
-    $bolt_ex_index++;
+    $bolt_ex->index++;
 }
 
 function image_rect($img, $rect) {
-    global $bolt_ex_mode;   // input
-    global $bolt_ex_index;  // input
-    global $bolt_ex_state;  // output if SHOW, else input
-    global $bolt_ex_score;  // incremental output if SCORE
+    global $bolt_ex;
 
-    parse_str($bolt_ex_query_string);
+    parse_str($bolt_ex->query_string);
 
-    switch ($bolt_ex_mode) {
+    switch ($bolt_ex->mode) {
     case BOLT_MODE_SHOW:
         echo "<img src=$img>";
         break;
diff --git a/html/user/bolt_sched.php b/html/user/bolt_sched.php
index 29e522fa32..b8eecd0755 100644
--- a/html/user/bolt_sched.php
+++ b/html/user/bolt_sched.php
@@ -178,10 +178,7 @@ function show_nav($links, $up_link, $view_id) {
 function show_item($iter, $view_id, $prev_view_id, $mode, $repeat=null) {
     global $user;
     global $course;
-    global $bolt_ex_mode;
-    global $bolt_ex_index;
-    global $bolt_ex_score;
-    global $bolt_query_string;
+    global $bolt_ex;
     global $refresh;
     global $url_args;
 
@@ -197,8 +194,8 @@ function show_item($iter, $view_id, $prev_view_id, $mode, $repeat=null) {
     $next = "<a href=bolt_sched.php?$url_args&action=next&view_id=$view_id><img src=img/next.gif></a>";
 
     if ($item->is_exercise()) {
-        $bolt_ex_mode = $mode;
-        $bolt_ex_index = 0;
+        $bolt_ex->mode = $mode;
+        $bolt_ex->index = 0;
         switch ($mode) {
         case BOLT_MODE_SHOW:
             echo "
@@ -220,7 +217,7 @@ function show_item($iter, $view_id, $prev_view_id, $mode, $repeat=null) {
         case BOLT_MODE_ANSWER:
             require($item->filename);
             if (function_exists('bolt_divide')) bolt_divide();
-            $score_pct = number_format($bolt_ex_score*100);
+            $score_pct = number_format($bolt_ex->score*100);
             echo "Score: $score_pct%";
             break;
         }
@@ -269,12 +266,10 @@ function show_item($iter, $view_id, $prev_view_id, $mode, $repeat=null) {
 // Show the student the results of an old exercise; no navigation items
 //
 function show_answer_page($iter, $score) {
-    global $bolt_ex_mode;
-    global $bolt_ex_index;
-    global $bolt_query_string;
+    global $bolt_ex;
 
-    $bolt_ex_mode = BOLT_MODE_ANSWER;
-    $bolt_ex_index = 0;
+    $bolt_ex->mode = BOLT_MODE_ANSWER;
+    $bolt_ex->index = 0;
 
     $item = $iter->item;
     page_header();
@@ -397,8 +392,8 @@ case 'prev':
             $v2 = BoltView::lookup_id($view->prev_view_id);
             $result = BoltResult::lookup_id($v2->result_id);
             srand($v2->id);
-            $bolt_ex_score = $result->score;
-            $bolt_ex_query_string = $result->response;
+            $bolt_ex->score = $result->score;
+            $bolt_ex->query_string = $result->response;
         }
         $view_id = create_view($iter, $mode, $view->prev_view_id);
         show_item($iter, $view_id, $view->prev_view_id, $mode);
@@ -461,22 +456,22 @@ case 'answer':          // submit answer in exercise
 
     // compute the score
 
-    $bolt_ex_query_string = $_SERVER['QUERY_STRING'];
-    $bolt_ex_mode = BOLT_MODE_SCORE;
-    $bolt_ex_index = 0;
-    $bolt_ex_score = 0;
+    $bolt_ex->query_string = $_SERVER['QUERY_STRING'];
+    $bolt_ex->mode = BOLT_MODE_SCORE;
+    $bolt_ex->index = 0;
+    $bolt_ex->score = 0;
     $bolt_query_string = $item->query_string;
     srand($view_id);
     ob_start();     // buffer output to avoid showing exercise text
     require($item->filename);
     ob_end_clean();
 
-    $bolt_ex_score /= $bolt_ex_index;
+    $bolt_ex->score /= $bolt_ex->index;
 
     if ($item->callback) {
         $user->bolt->attrs = unserialize($user->bolt->attrs);
         call_user_func(
-            $item->callback, $user, $bolt_ex_score, $bolt_ex_query_string
+            $item->callback, $user, $bolt_ex->score, $bolt_ex->query_string
         );
         $user->bolt->attrs = serialize($user->bolt->attrs);
         $attrs = $user->bolt->attrs;
@@ -489,7 +484,7 @@ case 'answer':          // submit answer in exercise
     $now = time();
     $result_id = BoltResult::insert(
         "(create_time, user_id, course_id, view_id, item_name, score, response)
-        values ($now, $user->id, $course->id, $view->id, '$view->item_name', $bolt_ex_score, '$qs')"
+        values ($now, $user->id, $course->id, $view->id, '$view->item_name', $bolt_ex->score, '$qs')"
     );
     $view->update("result_id=$result_id");
 
@@ -499,7 +494,7 @@ case 'answer':          // submit answer in exercise
     $xset = $iter->xset;
     if ($xset) {
         $is_last = $xset->xset_record_score(
-            $iter, $bolt_ex_score, $view->id, $avg_score, $repeat
+            $iter, $bolt_ex->score, $view->id, $avg_score, $repeat
         );
         if ($repeat) $repeat->avg_score = $avg_score;
         if ($is_last) {
@@ -553,7 +548,7 @@ case 'answer_page':
     }
     $result = BoltResult::lookup_id($view->result_id);
     srand($view_id);
-    $bolt_ex_query_string = $result->response;
+    $bolt_ex->query_string = $result->response;
     show_answer_page($iter, $result->score);
     break;
 case 'course_home':
@@ -636,9 +631,9 @@ case 'resume':
         $view_orig = BoltView::lookup_id($view->prev_view_id);
         $result = BoltResult::lookup_id($view_orig->result_id);
         srand($view_orig->id);
-        $bolt_ex_query_string = $result->response;
-        $bolt_ex_score = $result->score;
-        $bolt_ex_index = 0;
+        $bolt_ex->query_string = $result->response;
+        $bolt_ex->score = $result->score;
+        $bolt_ex->index = 0;
         $view_id = create_view($iter, $mode, $view_orig->id);
         show_item($iter, $view_id, $view_orig->id, $mode);
     } else {