diff --git a/01_grundlagen/unterricht/tag07/09_str-trim.html b/01_grundlagen/unterricht/tag07/09_str-trim.html
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+++ b/01_grundlagen/unterricht/tag07/09_str-trim.html
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+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>String.trim()</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>
+          <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/String/trim">
+            String.trim()
+          </a>
+        </h1>
+        <p>
+          Die <strong>trim()</strong> Methode entfernt Leerzeichen an beiden Enden einer Zeichenfolge. Das betrifft
+          Leerzeichen verschiedenster Art (space, tab, no-break space, etc.) und alle Zeilenumbruch einleitende Zeichen
+          (LF, CR, etc.).
+        </p>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      let name = '   Ladislaus Jones     ';
+
+      // String Methode - str.trim()
+
+      console.log(name.trim()); // => "Ladislaus Jones" (without space before and after)
+      console.log('\t \n lorem ipsum \t '.trim()); // => "lorem ipsum"
+
+      // String Methode - str.trimStart() | str.trimLeft()
+      console.log('  lorem ipsum   '.trimStart()); //=> 'lorem ipsum   '
+
+      // String Methode - str.trimEnd() | str.trimRight()
+      console.log('  lorem ipsum   '.trimEnd()); //=> '   lorem ipsum'
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag07/10_str-char-at.html b/01_grundlagen/unterricht/tag07/10_str-char-at.html
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+++ b/01_grundlagen/unterricht/tag07/10_str-char-at.html
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+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>String.charAt()</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>
+          <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/String/charAt">
+            String.charAt()
+          </a>
+        </h1>
+        <p>Die <strong>charAt()</strong>-Methode gibt das Zeichen an einer bestimmten Stelle eines Strings wieder.</p>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      const firstName = 'Ladislaus';
+      const lastName = 'Jones';
+
+      console.log(`${lastName}, ${firstName.charAt(0)}.`); // => "Jones, L."
+
+      // String - Methode str.charAt(index)
+
+      console.log('Lisa Simpos'.charAt(0)); // => 'L'
+      console.log('Lisa Simpon'.charAt(5)); // => 'S'
+
+      // Default-Wert bei keiner Angabe ist 0
+      console.log('Lisa Simpos'.charAt()); // => 'L'
+
+      // Indexoperator []
+      console.log('Lisa Simpson'[0]); //=> 'L'
+      console.log('Lisa Simpson'[5]); //=> 'S'
+
+      console.log('Lisa Simpson'.charAt(999)); // => ''
+      console.log('Lisa Simpson'.charAt(-999)); // => ''
+
+      // https://asciitable.xyz/
+      console.log('Lisa Simpson'.charCodeAt(5)); // => 'S' -> 83
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag07/11_str-to-lower-upper-case.html b/01_grundlagen/unterricht/tag07/11_str-to-lower-upper-case.html
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+++ b/01_grundlagen/unterricht/tag07/11_str-to-lower-upper-case.html
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+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>String.toLowerCase() | String.toUpperCase()</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>
+          <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLowerCase">
+            String.toLowerCase()
+          </a>
+          &amp;
+          <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase">
+            String.toUpperCase()
+          </a>
+        </h1>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      const firstName = 'ladislaus';
+      const lastName = 'JOnes';
+
+      // ucfirst
+      const transformedFirstName = `${firstName.charAt(0).toUpperCase()}${firstName.substring(1).toLowerCase()}`;
+      const transformedLastName = `${lastName.charAt(0).toUpperCase()}${lastName.substring(1).toLowerCase()}`;
+
+      console.log(`${transformedFirstName} ${transformedLastName}`);
+
+      // String Methode - str.toLowerCase()
+
+      console.log('LOREM Ipsum'.toLowerCase()); // => 'lorem ipsum'
+
+      // String Methode - str.toUpperCase()
+
+      console.log('Lorem Ipsum'.toUpperCase()); // => 'LOREM IPSUM'
+    </script>
+  </body>
+</html>