Pipet Not Filling in Titration Lab

Myself and at least one student have had trouble filling the 25 mL pipet in the titration of unknown HCl with NaOH (Beyond Labz Assessment)(Titrations).

Sometimes the pipet fills and drains fine (Image A of the attached jpeg).
Sometimes the pipet only half-fills. I assume that is because there is not enough solution in the beaker from which it is being withdrawn. It would really help if the procedure mentioned this (image B of attachment).
Sometimes the pipet has dark and light bands after filling and does not seem to drain out anything. This does not seem to be related to amount of solution in the beaker from which it is drawn (image C of attachment). HOW DO I EXPLAIN THIS TO STUDENTS?
Pipet

@cmuelle2
thank you for reaching out! I have adjusted that worksheet to directly explain how much needs to be in the beaker to start with. I appreciate the feedback on that.
I have never seen the dark & light band bug that you showed- that’s not good! I was just able to replicate that- so I will send that bug on to the developers to get fixed quickly for you. Thanks for letting us know.
Please let us know if you have any further issues.

Thanks. I have told my students that they can only submit the unknown HCl concentration once (since it looks like they get the same unknown every time and are told the true value after the first submission). Is there any way to reset the students’ unknowns so I can postpone the due date and give them another shot at it?

@cmuelle2 Yes, that is correct- an Assigned Unknown will always give the same unknown- every time. So if you want to give them another Assigned Unknown so they can have another chance, just generate a new preset link and send that out to them. You can make as many new Assignments for them as you many want to!

So just start from scratch- don’t start with one of our preset unknown links, because those already have an unknown assigned to them. Set up your experiment however you want them to have it and generate a new Practice Unknown link for yourself. In your Instructor portal convert that link to an Assigned Unknown and then send your new preset link to your students.
Please let us know if you have further questions!