Post Tests on a one-group pre-test/post-test research design

#1
I have conducted a survey as a pre-test. Is it okay for the post-test to be a semi-opened questionnaire regarding the same content. Will validity be an issue?
 

trinker

ggplot2orBust
#2
I have conducted a survey as a pre-test. Is it okay for the post-test to be a semi-opened questionnaire regarding the same content. Will validity be an issue?
I would say yes considering both measures are researcher made. How do you know they're measuring the same thing?