Subject: making samples to test for pH and Alkalinity

I am a teaching assistant at a university and creating some new labs for 
undergraduate non-science students.  I am creating a lab to help students 
understand the difference between pH and alkalinity.  I want them to test 
water samples that have the same pH but different alkalinities (hydroxide, 
carbonate, and bicarbonate).  What soluble compounds can I add to 
distilled water to achieve this?  And what proportions of the compounds 
should I add?

Thanks for your help.

Re: making samples to test for pH and Alkalinity