HI Mignon, Although this is hard for you, it just proves that these little upstarts have NO idea.
Try and relate to them and if you are young at heart you will be able to do this, it might take awhile but with the right attitude you will overcome this.

I once worked with a 17 year old when I was 50 and she became a lasting friend and I still have contact with her

Just a suggestion that worked very effectively on my son, who has a Dip Ed

Sorry Mignon, I did write a 7 line suggestion but can't post it on this site.

I wonder what advice would be given if this was a question of race or gender and why that difference exists? Regarding the last point, the dogs are barking that it is OK to discriminate on the basis of 'old' age and the government itself is responsible for fomenting intergenerational jealousy. The Australian Human Rights Commission is prepared to be proactive in its traditional, favoured areas of discrimination, but apparently reserves the right to be reactive - waiting for complaints - in the case of older Australians.

In response to Mignon, you are being subjected to bullying, but how severe that is you don't say. However if you are being sent to Coventry, being referred to by offensive nick-names or made the subject of jokes, being obstructed or not being informed of instructions that could affect your performance, that is extreme and should be reported to your supervisor and to the HR manager. No 'ifs' or 'buts', just be practical and businesslike and don't whinge. "This is something that is happening and I would like it nipped in the bud."

On the other hand if the banter is mild, doesn't escalate and otherwise you are welcomed into their midst, just be open and say to the offenders in front of the group that it offends you and would they mind giving it a break. Quietly make a written note in your diary of what was said without embellishment and the date/s. Apart from that, look and act modern, but do not react. Be aware that it is easy to appear judgemental about their behaviour too, especially when they are sharing notes about their extra-curricular activities.

As a manager and later as a small business owner I always preferred that a worker approached me sincerely, frankly and positively with any concern before it became something bigger. No competent manager tolerates any gossip nor negative stuff that could affect morale, productivity and the good name of the business.

Use your judgement and act.

Hi Mignon, been there done that, the way I handled it was to join in with their conversations, I didn't go into my shell, (which is what I wanted to do), I sat with them in the lunch room and talked about world affairs, anything outside of work, found out their interests outside of work and discussed those, sports family outings etc, it may sound like I pushed myself in but in the end I found they respected me and the thing that surprised me so much they started asking advice, try and let little things pass and ignore it, but as Nautilus said, if it is bullying I would follow Nautilus's advice.
The worst girl I had, she was 27, I was 53 and we worked in the same office, (she was at the interview when I went for the job), she was the only one on the board that didn't want me, (probably because of my age) so I was behind the eight ball before I started.

As aside to all that, a group of us sometimes go out for coffee of an evening after they have finished work.

Gain their respect and you will have no more problems. Good luck.

Thanks for all the advice. I needed some support.
I am used to working with younger staff when I work as a nurse in a hospital , and I am fine with that, as they are often bettter trained than me, so that isnt a problem.
These girls at the office seem to "teach" me most of the issues at hand but not all and delight to expose my errors when I make a mistake, and in front of patients.
I am always smiling and pleasant and ask about their weekend etc. But they continue to turn their backs and talk to each other and exclude me. I think they are very ignorant and I let most of this go through to the keeper, but it is hurtful and makes the working more difficult than it should be. I am not as fast as them on the computer either.
I am waiting to address these issues with a soon to be appointed Practice Manager.
My 17yr old son is very respectful and doesn't give me this kind of crap..
Thanks again. Mignon