It's kind of tough to give a real useful response, from such a brief description. Have to guess this is a school project, where the instructor already knows what you have learned, and what parts you have available. Unfortunately, we do not know anything more than what was stated. If you search the web, you should be able to find several simple designs, since this was done while I was in High School (30 years ago). Remember it being done with a PIC microcontroller using the ADC input and an LCD. I don't use PIC, so didn't save the source.
Kind of depends on if you are looking to use OP AMPs and LEDS, or a microcontroller. Use search on this site, believe this isn't the first time the topic has come up.