I am looking for an Instrument to use to judge if Pre-service teachers' have changed the way they think mathematics should be taught after experiences in classroom teaching.
It sounds like you are looking for a standard convergent instrument. I would caution against that. You should think about constructed an open-ended instrument. You could easily develop a question that asks teachers what you are interested in and administer it before and after. This type of "instrument" would not lend itself to quantification, and it shouldn't given your interests.
If an open-ended survey is not to your liking, you could develop a mathematics lesson (or use a video of a lesson) and use this is a pre and post prompt for your teachers' opinions about teaching mathematics.
I can't think of an instrument that has measured this specifically. You might be able to take an attitude measure and modify it to gauge how opinions have changed. I am certainly interested in what you discover - my sense is that it could be a negative experience for pre-service teachers as schools can be conservative in how they view mathematics education and also have to deal with the pressures of mandated curriculums, direct teaching, NAPLAN, parental expectations etc etc. Cheers, Kevin.
I agree with suggestions of open-ended instruments (I used open questionnaires, essays, etc.), but I'm skeptical about measurement of change of attitude, beliefs, emotions immediately after an intervention. Moreover, as Kevin undelines, I (and literature about that) believe that we have to be very cautios in assessing pre-service teachers' beliefs without observing them in practice.
I would like to recommend Jeppe Skott's work in Patterns of Participation. Hanna Palmér has used this framework when studying changes in prospective teachers conceptions: http://lnu.se/personal/hanna.palmer
You might look at Shannon McCampbell's Dissertation, University of New Mexico: "PRE-SERVICE TEACHERS’ SELF-EFFICACY FOR TEACHING MATHEMATICS" She used two instruments that speak to your interest: TEACH MATH Beliefs Survey Aguirre et al, 2010) , and Beliefs About Mathematics. (Allen, 2007)
Allen, G. D. (2007). What is a misconception? Unpublished manuscript. unpublished manuscript. Mathematics. Texas A&M University. Retrieved from http://www.math.tamu.edu/~snite/MisMath.pdf
There are many studies aout self-efficacy using the STEBI scale. No need to focus on an unpublished dissertation. More importantly, I think the original question about teachers' views abot teaching mathematics is much broader than self-efficacy.
Horizon Research, Inc. has developed a lot of instruments and questionaires over the years. One of theirs that comes to mind to address your study is
http://www.horizon-research.com/instruments/clas/tq_math.pdf , particularly parts A and B (the first page). Other parts get into the actual teaching in a classroom, which you could use if you observe your pre-service teachers in the field.
Horizon is sub-contracted by many NSF grants to evaluate their effectiveness and is well-respected in the research community. You may consider looking through this survey and modifying it to meet your needs. You could also use it to create some open-ended questions as Dr. Lederman suggests, and then you would be able to situate your study among others because of the similar topics explored.
One book that I would recommend you consult for this is Approaches to Studying the Enacted Mathematics Curriculum, an edited book by Heck, Chval, Weiss, & Ziebarth. There are multiple chapters detailing instruments used to study lesson enactment, use of curricular materials, etc. Both Heck and Weiss are from Horizon Research, and chapter authors include: D. Thompson, S. Senk, M. Huntley, L. Wilson, J. Tarr, D. Grouws, J. Freeman, M. Rudnick, J. Roseman, J. McMaken, A. Porter.