Hi Diane,
The problem seems to be that, unlike the Forum activity, the Glossary activity does not feature an "Aggregate type" setting*.
One workaround (for Moodle 1.9) in your case is as follows - tried and tested, it works!
- In your Glossary settings, Grade, select 24.
- When you grade your students' entries, give each entry a score of 24/24 if it's OK for you and 0/24 otherwise.
- When you have submitted all those Glossary grades, if you go to the Gradebook you will see that the students get a grade out of 24, which I hope is what you wanted.
- Example: if for one student you grade 18 of his 24 entries 24//24 and grade the remaining 6 entries 0/24, his final score for that activity will be 18/24. See attached screenshot.
Hope that helps.
Joseph
*EDIT.- This "bug" has been fixed in Moodle 2.