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://ocw.mit.edu/resources/res-21f-003-learning-chinese-a-foundation-course-in-mandarin-spring-2011/online-textbook/

http://web.csulb.edu/~txie/ccol/content.htm

http://www.archchinese.com/

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

http://www.chinesecom.eu/