To mark the launch of the Herschel and Planck space observatories, ESA has participated in the production of a wide-ranging series of educational materials related to these two missions. There are a number of documents available at the link below.
Homepage: Herschel and Planck in the classroom
However the documents of interest here are the exercise and solution documents on problems related to the Herschel Telscope. The links for these two documents are given below. For this content, there is material and supplementary information on red shift, in particular cosmological redshift. The solution document (pg 1 and 2) provides a detailed explanation of red and blue shift. In addition, the document points out that although redshift and blueshift of electromagnetic light seem to be similar to the Doppler effect for sound waves, it is in fact the expansion of space between the source and the earth that leads to the shifting of the wavelength of the electromagnetic waves.