Most of the measures will be of related constructs such as "subjective well-being" or "satisfaction with life." Ed Diener's Satisfaction with Life scale is good and very short. But I think you are looking for an immediate response to reading (or hearing) a story, right? For that, I would use a direct measure of current affect or mood state. These will usually include more than one type of emotion, but that's probably a good thing. (What if the fairy tale makes me scared or depressed?) The "Positive and Negative Affect Scale," (PANAS) is a good example; the PANAS-X is a nice extension of the original. You can download it here using the link below.

http://www2.psychology.uiowa.edu/faculty/watson/PANAS-X.pdf

I would use the Personal Wellbeing Index. I have attached  paper that supports it's equivalence in Adult and parallel form for children 12-18 years.  The PWI instruments are used by hundreds of researchers in over 50 countries, ans id the instrument of choice for members of the International Wellbeing Group.

The PWI adopts a domain based approach to measuring SWB (AKA happiness in mainstream), and the overall SWB composite score is taken the average of the 7 standardised domains.

Here is a link to the suite of Instruments:

http://www.acqol.com.au/iwbg/wellbeing-index/index.php

All the best,

Adrian

Here is a link to the 

Most of the measures will be of related constructs such as "subjective well-being" or "satisfaction with life." Ed Diener's Satisfaction with Life scale is good and very short. But I think you are looking for an immediate response to reading (or hearing) a story, right? For that, I would use a direct measure of current affect or mood state. These will usually include more than one type of emotion, but that's probably a good thing. (What if the fairy tale makes me scared or depressed?) The "Positive and Negative Affect Scale," (PANAS) is a good example; the PANAS-X is a nice extension of the original. You can download it here using the link below.

http://www2.psychology.uiowa.edu/faculty/watson/PANAS-X.pdf

Here is a useful website that contains info on a series of positive psychology questionnaires (including some of the ones previously mentioned), along with their references and PDFs of the questionnaires.

http://www.ppc.sas.upenn.edu/ppquestionnaires.htm

Short scales for happiness are Lyubomirsky's happiness scale that was cited above. another option is the positive affect scale taken from the SPAIN suggested by Diener et al. 2010. Nevertheless, it is possible that you would need to adapt these scales so they will fit for the porpuse of your study.

YES, happiness levels can be measured using several hormones as well the electrophysiological studies. anandamide and endorphins suggest the happiness levels in indidviduals. 

Dear Lidia,

If you are not only interested in emotional/subjective well-being, but in a more comprehensive measure of well-being, I would advise the Mental Health Continuum - Short Form (MHC-SF(. It is a validated instrument, based on theory, with 14 items, which measures emotional, psychological and social well-being.

Greetings,

Laura

If you look on this site at the questionnaires you will find Authentic Happines Inventory. I think that if you write to the author he will give you the right to use it and the documents you need. Hope this will help you. https://www.authentichappiness.sas.upenn.edu/home

You may wish to have a look at the Flourishing Scale, based on Seligman's (2011) PERMA model. See this work for more details:

Diener, E., Wirtz, D., TOV, William, Kim-Prieto, C., Choi, D., Oishi, S., & Biswas-Diener, R..(2010). New Well-Being Measures: Short Scales to Assess Flourishing and Positive and Negative Feelings. Social Indicators Research, 97(2), 143-156.

Regards, Sebastian