diff --git a/.idea/misc.xml b/.idea/misc.xml
index 07de02a..b7bb25f 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -14,6 +14,7 @@
     <cargoProject FILE="$PROJECT_DIR$/structs/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/rectangles/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/enums/Cargo.toml" />
+    <cargoProject FILE="$PROJECT_DIR$/modules/Cargo.toml" />
   </component>
   <component name="ComposerJsonPluginSettings">
     <unboundedVersionInspectionSettings>
diff --git a/.idea/rust.iml b/.idea/rust.iml
index 58d5604..88c150b 100644
--- a/.idea/rust.iml
+++ b/.idea/rust.iml
@@ -55,6 +55,10 @@
       <sourceFolder url="file://$MODULE_DIR$/enums/examples" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/enums/tests" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/enums/benches" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/modules/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/modules/examples" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/modules/tests" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/modules/benches" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/branches/target" />
       <excludeFolder url="file://$MODULE_DIR$/ctof/target" />
       <excludeFolder url="file://$MODULE_DIR$/enums/target" />
@@ -62,6 +66,7 @@
       <excludeFolder url="file://$MODULE_DIR$/functions/target" />
       <excludeFolder url="file://$MODULE_DIR$/guessing_game/target" />
       <excludeFolder url="file://$MODULE_DIR$/loops/target" />
+      <excludeFolder url="file://$MODULE_DIR$/modules/target" />
       <excludeFolder url="file://$MODULE_DIR$/rectangles/target" />
       <excludeFolder url="file://$MODULE_DIR$/references/target" />
       <excludeFolder url="file://$MODULE_DIR$/scope/target" />
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 1de8081..d7cf9de 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -1,7 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ChangeListManager">
-    <list default="true" id="c8f42924-1cd2-4b1c-bcff-602a3368bb16" name="Default Changelist" comment="" />
+    <list default="true" id="c8f42924-1cd2-4b1c-bcff-602a3368bb16" name="Default Changelist" comment="">
+      <change beforePath="$PROJECT_DIR$/.idea/misc.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/misc.xml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/.idea/rust.iml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/rust.iml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
+    </list>
     <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -11,16 +15,23 @@
   <component name="FileEditorManager">
     <leaf SIDE_TABS_SIZE_LIMIT_KEY="300">
       <file pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/enums/src/main.rs">
+        <entry file="file://$PROJECT_DIR$/guessing_game/.gitignore">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="440">
-              <caret line="30" column="7" selection-start-line="30" selection-start-column="7" selection-end-line="30" selection-end-column="7" />
+            <state relative-caret-position="32">
+              <caret line="2" column="5" selection-start-line="2" selection-start-column="5" selection-end-line="2" selection-end-column="5" />
             </state>
           </provider>
         </entry>
       </file>
     </leaf>
   </component>
+  <component name="FileTemplateManagerImpl">
+    <option name="RECENT_TEMPLATES">
+      <list>
+        <option value="Rust File" />
+      </list>
+    </option>
+  </component>
   <component name="FindInProjectRecents">
     <findStrings>
       <find>ftoc</find>
@@ -30,7 +41,7 @@
     </replaceStrings>
   </component>
   <component name="Git.Settings">
-    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/enums" />
+    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/guessing_game" />
   </component>
   <component name="IdeDocumentHistory">
     <option name="CHANGED_PATHS">
@@ -48,6 +59,11 @@
         <option value="$PROJECT_DIR$/rectangles/src/main.rs" />
         <option value="$PROJECT_DIR$/.gitignore" />
         <option value="$PROJECT_DIR$/enums/src/main.rs" />
+        <option value="$PROJECT_DIR$/modules/src/sound.rs" />
+        <option value="$PROJECT_DIR$/modules/src/performance_group.rs" />
+        <option value="$PROJECT_DIR$/modules/src/main.rs" />
+        <option value="$PROJECT_DIR$/modules/src/sound/instrument.rs" />
+        <option value="$PROJECT_DIR$/guessing_game/.gitignore" />
       </list>
     </option>
   </component>
@@ -67,11 +83,26 @@
     <ConfirmationsSetting value="1" id="Add" />
   </component>
   <component name="ProjectView">
-    <navigator proportions="" version="1">
+    <navigator currentView="Scope" currentSubView="Scope 'Project Files'; set:Project Files; class com.intellij.psi.search.scope.ProjectFilesScope" proportions="" version="1">
       <foldersAlwaysOnTop value="true" />
     </navigator>
     <panes>
-      <pane id="Scope" />
+      <pane id="Scope">
+        <subPane subId="Scope 'Project Files'; set:Project Files; class com.intellij.psi.search.scope.ProjectFilesScope">
+          <expand>
+            <path>
+              <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
+              <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
+            </path>
+            <path>
+              <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
+              <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
+              <item name="guessing_game" type="9f88c78c:ScopeViewTreeModel$FileNode" />
+            </path>
+          </expand>
+          <select />
+        </subPane>
+      </pane>
       <pane id="PackagesPane" />
       <pane id="ProjectPane">
         <subPane>
@@ -80,6 +111,17 @@
               <item name="rust" type="b2602c69:ProjectViewProjectNode" />
               <item name="rust" type="462c0819:PsiDirectoryNode" />
             </path>
+            <path>
+              <item name="rust" type="b2602c69:ProjectViewProjectNode" />
+              <item name="rust" type="462c0819:PsiDirectoryNode" />
+              <item name="modules" type="462c0819:PsiDirectoryNode" />
+            </path>
+            <path>
+              <item name="rust" type="b2602c69:ProjectViewProjectNode" />
+              <item name="rust" type="462c0819:PsiDirectoryNode" />
+              <item name="modules" type="462c0819:PsiDirectoryNode" />
+              <item name="src" type="462c0819:PsiDirectoryNode" />
+            </path>
           </expand>
           <select />
         </subPane>
@@ -88,7 +130,7 @@
   </component>
   <component name="PropertiesComponent">
     <property name="JavaScriptWeakerCompletionTypeGuess" value="true" />
-    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1548878099464" />
+    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1548879558121" />
     <property name="javascript.nodejs.core.library.configured.version" value="7.1.0" />
     <property name="js.eslint.eslintPackage" value="$USER_HOME$/.yarn-config/global/node_modules/.bin/eslint" />
     <property name="js.eslint.nodeInterpreter" value="project" />
@@ -116,7 +158,7 @@
       </list>
     </option>
   </component>
-  <component name="RunManager" selected="Cargo Command.Run enums">
+  <component name="RunManager" selected="Cargo Command.Run modules">
     <configuration name="&lt;template&gt;" type="TestNG" default="true" selected="false">
       <option name="MAIN_CLASS_NAME" />
       <option name="VM_PARAMETERS" value="-ea" />
@@ -145,6 +187,16 @@
       <envs />
       <method v="2" />
     </configuration>
+    <configuration name="Run modules" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
+      <option name="channel" value="DEFAULT" />
+      <option name="command" value="run --package modules --bin modules" />
+      <option name="allFeatures" value="false" />
+      <option name="nocapture" value="false" />
+      <option name="backtrace" value="SHORT" />
+      <option name="workingDirectory" value="file://$PROJECT_DIR$/modules" />
+      <envs />
+      <method v="2" />
+    </configuration>
     <configuration name="Run rectangles" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
       <option name="channel" value="DEFAULT" />
       <option name="command" value="run --package rectangles --bin rectangles" />
@@ -155,16 +207,6 @@
       <envs />
       <method v="2" />
     </configuration>
-    <configuration name="Run references" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
-      <option name="channel" value="DEFAULT" />
-      <option name="command" value="run --package references --bin references" />
-      <option name="allFeatures" value="false" />
-      <option name="nocapture" value="false" />
-      <option name="backtrace" value="SHORT" />
-      <option name="workingDirectory" value="file://$PROJECT_DIR$/references" />
-      <envs />
-      <method v="2" />
-    </configuration>
     <configuration name="Run slices" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
       <option name="channel" value="DEFAULT" />
       <option name="command" value="run --package slices --bin slices" />
@@ -194,11 +236,11 @@
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="Cargo Command.Run modules" />
         <item itemvalue="Cargo Command.Run enums" />
         <item itemvalue="Cargo Command.Run rectangles" />
         <item itemvalue="Cargo Command.Run structs" />
         <item itemvalue="Cargo Command.Run slices" />
-        <item itemvalue="Cargo Command.Run references" />
       </list>
     </recent_temporary>
   </component>
@@ -206,7 +248,7 @@
     <frame x="1920" y="-438" width="1080" height="1897" extended-state="0" />
     <editor active="true" />
     <layout>
-      <window_info content_ui="combo" id="Project" order="0" sideWeight="0.4970809" visible="true" weight="0.2540132" />
+      <window_info active="true" content_ui="combo" id="Project" order="0" sideWeight="0.4970809" visible="true" weight="0.2540132" />
       <window_info id="Structure" order="1" sideWeight="0.5029191" side_tool="true" visible="true" weight="0.2540132" />
       <window_info id="Image Layers" order="2" />
       <window_info id="Designer" order="3" />
@@ -215,7 +257,7 @@
       <window_info id="Cargo" order="6" sideWeight="0.49791494" weight="0.3286119" />
       <window_info anchor="bottom" id="Message" order="0" />
       <window_info anchor="bottom" id="Find" order="1" />
-      <window_info active="true" anchor="bottom" id="Run" order="2" visible="true" weight="0.32979318" />
+      <window_info anchor="bottom" id="Run" order="2" visible="true" weight="0.32979318" />
       <window_info anchor="bottom" id="Debug" order="3" weight="0.4" />
       <window_info anchor="bottom" id="Cvs" order="4" weight="0.25" />
       <window_info anchor="bottom" id="Inspection" order="5" weight="0.4" />
@@ -344,10 +386,60 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/.idea/workspace.xml">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="368">
+          <caret line="23" column="40" selection-start-line="23" selection-start-column="40" selection-end-line="23" selection-end-column="40" />
+        </state>
+      </provider>
+    </entry>
     <entry file="file://$PROJECT_DIR$/enums/src/main.rs">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="440">
-          <caret line="30" column="7" selection-start-line="30" selection-start-column="7" selection-end-line="30" selection-end-column="7" />
+        <state relative-caret-position="672">
+          <caret line="42" column="16" lean-forward="true" selection-start-line="42" selection-start-column="16" selection-end-line="42" selection-end-column="16" />
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/modules/src/sound.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="16">
+          <caret line="1" lean-forward="true" selection-start-line="1" selection-end-line="1" />
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/modules/src/sound/instrument.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="48">
+          <caret line="3" lean-forward="true" selection-start-line="3" selection-end-line="3" />
+          <folding>
+            <element signature="e#18#19#0" expanded="true" />
+            <element signature="e#60#61#0" expanded="true" />
+          </folding>
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/modules/src/performance_group.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="96">
+          <caret line="6" column="1" selection-start-line="6" selection-start-column="1" selection-end-line="6" selection-end-column="1" />
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/modules/src/main.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="96">
+          <caret line="6" lean-forward="true" selection-start-line="6" selection-end-line="6" />
+          <folding>
+            <element signature="e#366#367#0" expanded="true" />
+            <element signature="e#390#391#0" expanded="true" />
+          </folding>
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/guessing_game/.gitignore">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="32">
+          <caret line="2" column="5" selection-start-line="2" selection-start-column="5" selection-end-line="2" selection-end-column="5" />
         </state>
       </provider>
     </entry>
diff --git a/guessing_game/.gitignore b/guessing_game/.gitignore
index 53eaa21..2bb8d25 100644
--- a/guessing_game/.gitignore
+++ b/guessing_game/.gitignore
@@ -1,2 +1,3 @@
 /target
 **/*.rs.bk
+.idea
diff --git a/modules/Cargo.toml b/modules/Cargo.toml
new file mode 100644
index 0000000..0301914
--- /dev/null
+++ b/modules/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "modules"
+version = "0.1.0"
+authors = ["Timothy Warren <twarren@nabancard.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/modules/src/main.rs b/modules/src/main.rs
new file mode 100644
index 0000000..2be7df9
--- /dev/null
+++ b/modules/src/main.rs
@@ -0,0 +1,6 @@
+mod sound;
+mod performance_group;
+
+fn main() {
+    performance_group::clarinet_trio();
+}
diff --git a/modules/src/performance_group.rs b/modules/src/performance_group.rs
new file mode 100644
index 0000000..52281a3
--- /dev/null
+++ b/modules/src/performance_group.rs
@@ -0,0 +1,7 @@
+use crate::sound::instrument;
+
+pub fn clarinet_trio() {
+    instrument::clarinet();
+    instrument::clarinet();
+    instrument::clarinet();
+}
diff --git a/modules/src/sound.rs b/modules/src/sound.rs
new file mode 100644
index 0000000..866ac56
--- /dev/null
+++ b/modules/src/sound.rs
@@ -0,0 +1 @@
+pub mod instrument;
diff --git a/modules/src/sound/instrument.rs b/modules/src/sound/instrument.rs
new file mode 100644
index 0000000..651789d
--- /dev/null
+++ b/modules/src/sound/instrument.rs
@@ -0,0 +1,3 @@
+pub fn clarinet() {
+    println!("A clarinet is playing.");
+}