These are all language learning resources, mostly following a course but, of course, you can extract material which is relevant. All these resources have been found through the use of Open Educational Resources (OERs), which are a great source of free material. Please credit when you use them.
http://www.languageguide.org/mandarin/vocabulary/ – really fun – roll over images, word is said alongside character and pinyin displayed
http://www.learnnc.org/lp/editions/mandarin1/
http://www.learnnc.org/lp/editions/mandarin2/
http://www.learnnc.org/lp/editions/mandarin3/
http://www.learnnc.org/lp/editions/mandarin4/
http://www.bbc.co.uk/languages/chinese/real_chinese/
http://cctv.cntv.cn/lm/learningchinese/program/index.shtml
http://web.csulb.edu/~txie/ccol/content.htm
http://www.chinese-tools.com/learn/chinese/contents.html
https://en.wikibooks.org/wiki/Chinese_%28Mandarin%29
http://sites.la.utexas.edu/chinese/
http://www.linguanet-worldwide.org/lnetrest/#/?tl=Chinese
http://www.china.org.cn/e-learning/28.htm
http://www.learnchineseeveryday.com/
Practical Chinese Reader self-tests http://web.csulb.edu/~txie/PCRopen/selftest.htm