diff --git a/frontend/src/utils/exam-correct/exam-correct.js b/frontend/src/utils/exam-correct/exam-correct.js
index f9ab25fa7..aa76ea9ad 100644
--- a/frontend/src/utils/exam-correct/exam-correct.js
+++ b/frontend/src/utils/exam-correct/exam-correct.js
@@ -1,7 +1,7 @@
 import { Utility } from '../../core/utility';
 import { StorageManager, LOCATION } from '../../lib/storage-manager/storage-manager';
 
-// import './exam-correct.sass';
+import './exam-correct.sass';
 
 import moment from 'moment';
 
@@ -12,6 +12,8 @@ const EXAM_CORRECT_SEND_BTN_ID = 'exam-correct__send-btn';
 const EXAM_CORRECT_PARTICIPANT_INPUT_ID = 'exam-correct__participant';
 const EXAM_CORRECT_INPUT_BODY_ID = 'exam-correct__new';
 
+const INPUT_EMPTY_CLASS = 'input--invalid';
+
 
 @Utility({
   selector: `table[${EXAM_CORRECT_IDENT}]`,
@@ -51,9 +53,9 @@ export class ExamCorrect {
   }
 
   destroy() {
-    // TODO work in progress
     this._sendBtn.removeEventListener('click', this._sendCorrectionHandler);
     this._participantInput.removeEventListener('change', this._validateParticipantInput);
+    this._participantInput.removeEventListener('input', this._removeInputEmptyClassHandler);
   }
 
   _validateParticipantInput(event) {
@@ -63,18 +65,36 @@ export class ExamCorrect {
   _sendCorrectionHandler(event) {
     console.log('WIP _sendCorrectionHandler', event);
 
+    // refocus participant input element for convenience
+    this._participantInput.focus();
+
     const participant = this._participantInput.value;
+
+    // abort send if the participant input is empty
+    if (!participant) {
+      this._participantInput.classList.add(INPUT_EMPTY_CLASS);
+      this._participantInput.addEventListener('input', this._removeInputEmptyClassHandler.bind(this), { once: true });
+      return;
+    }
+
     const results = {};
     this._partInputs.forEach((input) => {
       if (input.value && !isNaN(input.value)) {
+        // TODO instead of ignoring NaN values, abort send and add error class to corresponding input
+        // (latter is optional)
         const partKey = input.getAttribute(EXAM_CORRECT_PART_INPUT_ATTR);
         if (!partKey) throw new Error('Exam part input without part attribute!');
-        results[partKey] = input.value;
+        results[partKey] = parseFloat(input.value);
       }
     });
 
+    // abort send if there are no results (after validation)
+    if (results === {}) return;
+
     console.log(participant, results);
 
+    // TODO apply row and data classes
+    // (maybe create some sort of template for this instead)
     const correctionRow = document.createElement('TR');
     const dateTD = document.createElement('TD');
     dateTD.appendChild(document.createTextNode(moment().format()));
@@ -91,11 +111,8 @@ export class ExamCorrect {
     const tableBody = this._element.querySelector(`tbody:not(#${EXAM_CORRECT_INPUT_BODY_ID})`);
     tableBody.insertBefore(correctionRow, tableBody.firstChild);
 
-    this._participantInput.value = null;
-    console.log(this._partInputs);
-    this._partInputs.forEach((input) => {
-      input.value = null;
-    });
+    // clear input values on validation success
+    [this._participantInput, ...this._partInputs].forEach(clearInput);
 
     const url = 'TODO';
     const headers = {};
@@ -103,6 +120,7 @@ export class ExamCorrect {
       participant: participant,
       results: results,
     };
+
     this._app.httpClient.post({
       url: url,
       headers: headers,
@@ -110,13 +128,37 @@ export class ExamCorrect {
     }).then(
       (response) => response.json()
     ).then(
-      (response) => this._processResponse(response)
+      (response) => this._processResponse(response, participant)
     ).catch((error) => {
-      // TODO
-      console.error('Error while processing response', error, body);
+      console.error('Error while processing response', error);
     });
 
     // TODO wait for response and replace status icon accordingly (add edit button to paste content in current input)
   }
 
+  _processResponse(response, participant) {
+    console.log('WIP ExamCorrect._processResponse', response, participant);
+    
+    // TODO find the first corresponding row (participant matches cell entry in second column) top-down
+    // if found:
+    //   if the response status is 'success' (i.e. the results have been upserted into the DB),
+    //     replace loading spinner in this row with tick mark icon
+    //   otherwise, 
+    //     replace loading spinner with error icon (error message as tooltip if present?)
+  }
+
+  _removeInputEmptyClassHandler() {
+    console.log('removeclass');
+    if (this._participantInput.value) {
+      this._participantInput.classList.remove(INPUT_EMPTY_CLASS);
+    } else {
+      this._participantInput.addEventListener('input', this._removeInputEmptyClassHandler, { once: true });
+    }
+  }
+
+}
+
+// TODO move to general util section?
+function clearInput(inputElement) {
+  inputElement.value = null;
 }
diff --git a/frontend/src/utils/exam-correct/exam-correct.sass b/frontend/src/utils/exam-correct/exam-correct.sass
new file mode 100644
index 000000000..a6a646bed
--- /dev/null
+++ b/frontend/src/utils/exam-correct/exam-correct.sass
@@ -0,0 +1,2 @@
+#exam-correct__participant.input--invalid
+  border: 2px solid var(--color-error)