diff --git a/event_routing_backends/processors/xapi/constants.py b/event_routing_backends/processors/xapi/constants.py
index 0d2a7cec..39bfe022 100644
--- a/event_routing_backends/processors/xapi/constants.py
+++ b/event_routing_backends/processors/xapi/constants.py
@@ -55,6 +55,7 @@
 XAPI_ACTIVITY_PRACTICE_ASSESSMENT = 'https://w3id.org/xapi/openedx/activity/practice-assessment'
 XAPI_ACTIVITY_PROCTORED_ASSESSMENT = 'https://w3id.org/xapi/openedx/activity/proctored-assessment'
 XAPI_ACTIVITY_PROGRESS = 'https://w3id.org/xapi/cmi5/result/extensions/progress'
+XAPI_ACTIVITY_LESSON = 'http://adlnet.gov/expapi/activities/lesson'
 
 # xAPI context
 XAPI_CONTEXT_VIDEO_LENGTH = 'https://w3id.org/xapi/video/extensions/length'