To report this colleague?

I think you need to be more proactive here. The reality is that you have been tasked with training this person. That training is NOT going well - she is not learning, she is making mistakes, and instead of learning from those mistakes, you are simply correcting them yourself. This is not doing you or her any favours and you run the risk that you are blamed for her incompetence once you take a step back.

You need to go to your line manager and/or hers (whoever is responsible for assigning you this task). You need to be clear and not defensive that unfortunately, you have concerns about her ability to do the job. Explain what you have tried to teach her, and where the mistakes are happening. Lightly mention that this is exacerbated by her finding it frustrating if she is asked to correct tasks and that she gets defensive, making it even more difficult to correct things.

Suggest to the relevant line manager that if this is simply a personality clash, someone else training her might be a better option. or, if it must be you, ask for some intervention. Perhaps a three way session to go through tasks and challenges and to get any challenges she perceives to be there out of the way. Or perhaps you suggest that you will provide a daily/weekly log of any mistakes and how you have attempted to show her the correct way.

Be clear in your own mind here - this is about you making it clear that this employee is not working out. You believe that she is unlikely to correct these mistakes, even with a different trainer, but that perhaps that is worth exploring in the first instance to give her every chance to improve. Be honest with yourself - this is not someone you want to stay in this role, you dont' think she can do it, and you certainly don't think that this is someone you want to work with. It's tough and no one wants to be the bad guy, but you might need to be here.

Being an asset to the team is not just capability of doing the job but behaviours too. I think you should be flagging to your managers that she seems averse to constructive feedback. Flag that in writing alongside your concerns about quality. If you don't, it's no good saying later down the line "oh yes she was a nightmare when I trained her too" and Will reflect poorly.

In the meantime, stop apologising! If she says she's not stupid, just say calmly but firmly "I didn't say you were. But it's my job to train you and that involves highlighting errors so they can be corrected for next time". Dont engage further.

Also, the first time you stand up to her and stop her snapping, I guarantee she won't do it again.

I don’t know how you are still be polite. - Don’t call me stupid - I would reply with I didn't, you need to do X.

Anyone who uses intimidation is bullying - end of.

Like others have said - send requests / instructions in email, if she tries to give a verbal reply ask her to confirm in email. If she doesn’t follow either a summary for her to confirm. Raise with her line manager their prickly nature and why you are using email to confirm communications.

Oh - and point her to the stationary cupboard, don’t lend her anything

In other words - gray rock her

Excellent advice

Yes, I hear you. She doesn't like you, in particular, pointing out her errors. Well tough, she needs to be know so she can correct them. Don't let this ruin your own job anymore because you don't deserve that. The email advice is great. Start with that paper trail and if her nonsense continues you need to escalate things. If this is a medical environment her mistakes could be costly. Sorry, haven't RTFT if you've already mentioned that. Good luck and don't take her shit anymore. You are in the right.

Agree with this. DON'T apologise!
I'd also say, in a calm voice, 'It's not appropriate to use words like stupid and I'm not going to engage on an emotional level. Please mind your tone and keep it professional. Factually, there are some things I need you to note for the good of the business...' and carry on enumerating them.

At this stage, I would be communicating by email with this person, so that there is a trackable record of the points that you are raising and she can't complain that you are speaking to her like she is stupid etc etc. I would also be emailing a summary of any tasks that you have given her. So you can say "for both our records, I am emailing confirmation of what we agreed to do today: blah, blah, blah." Then there can be no misunderstandings and as long as your emails are professional, she won't have a leg to stand on!

If necessary, copy in your manager on the emails.

I don't think this is an age thing, I think this is a poor work attitude thing. She sounds really unpleasant. I'm sorry you are having to to deal with this @WorkplaceDramaHelp

She sounds like a grade A moron. Keep a log of it. It sucks, humans!!!!

how is the training carried out? do you have a manual?
Go through each thing, and then each of you sign the training document to say, for her, she has understood the training and can do the task, and you to say she has understood the training and can do the task.

Keep on training until the tasks don't have mistakes.

Tell her you are not deaf either the next time she says she is not stupid

The big thing to take away from this is you are not her line manager, you are not responsible for correcting her work. You were asked to complete some training with her whilst a colleague was off sick. Time to return responsibility to that colleague who is now back and her line manager . if your responsibility is a peer checking role now, then any mistakes get returned to her before they get sent out. When returning it, cc her line manager. Ask to speak to her line manager and clarify what your role is, stick to it like glue. I have a senior colleague who I produce a lot of documentation for, she is very much a 'likes you one minute hates you the next' person. However much she may wish, she isn't my line manager but I am expected to correct mistakes. When it became too obvious that she was in fact bullying and trying to throw me under the proverbial bus, I arranged a meeting with my line manager to establish what the expectations of me and my working relationship with senior colleague actually are. That's what needs to be clarified here, that you may not be her manager, but the expectation is that she will be responsive to your training and corrections
For personal comments etc, keep a journal, stay factual, date, time, actual comment made.

Just to reiterate, you are helping her pass her probation by correcting her mistakes and keeping schtum as to her shitty attitude.

Let her make her mistakes for all to see, try and speak to her when you have witnesses, as I guess she won't be so snappy!

Definitely go see HR next time she oversteps.

OP it sounds very unprofessional in your work place. This not your fault at all. There should be a proper training system in place that is consistent and documented and training should be done by people trained to train, IYSWIM. Not dumped on somebody who already has their own work to do.

When she makes snide comments as you walk past can you draw attention to them by asking her to repeat or I saw a good way to call comments out is to say you don't understand and can they explain it please. It makes them go into detail about their comment/joke and that actually it's not funny and makes them think twice before doing it again.

It's horrible, isn't it. I hope you have more luck / better support than I did! You're in a good position though with her still being on probation. 😦
(There's a random emoji I've done by mistake and it won't delete. D'oh)

Whatever you do don't mention age, etc just keep it factual when you speak with your manager. It's highly likely it's not only you she is treating like this.

I've been there, it's hard work, but the attitude and repeated errors will not help her pass her probation. Document everything. Stop apologising for giving instruction and asking for errors to be fixed.

She's clearly determined to fail her probation! Stop correcting her work for her, report her to your line manager, and move on.

I was bullied out of a job. It took her years, but in the end, I took an escape route when I found one.

Logging ALL THE INCIDENTS is really important (not that it did me much good in the end!). Especially the ones that seem too stupid and petty to make a fuss about - because when you see them there, listed, it becomes apparent how often she does it. Yeah, you feel like you're being petty if you go " I heard her whispering about me as I walked past yesterday, and, umm, last week she hid my mug?", but trust me, that list of childish hostile actions that happened over 2 weeks, several every day, shows that you're not being sensitive. It's really wearing, much more than actual, substantial disagreements.

Off the top of my head, for you to chuckle at: In my workplace, one of the weekend staff once left a note about something that the first person in on monday morning would need to know. Not being sure who that would be, they addressed it to:
Bully'sName / MyName / Whoever is working!
I saw it first.
Later in the day, my name had been scribbled out so savagely, the paper was torn. Just one of the many things 🤷

It makes complete sense that this situation is wearing you down. What you’re describing isn’t just “teething problems” anymore — it’s a pattern of behaviour that’s affecting your ability to do your job and your sense of safety and comfort at work. No one should be entering the building with a knot in their stomach or coordinating their arrival to avoid someone.
What you’re experiencing is valid
You’re not overreacting. Being snapped at, undermined, whispered about, or treated differently when you’re alone with someone creates a hostile atmosphere. That’s not “just personality differences” — it’s behaviour that impacts your wellbeing and your work. This isn’t your job to fix alone. Ask for a meeting formal with your line manager and take along a piece of paper and make notes.

You’ve already taken the reasonable steps:
You’ve given polite, factual corrections.
You’ve avoided commenting on tone.
You’ve escalated the work errors to your line manager.
And instead of improving, the behaviour has escalated. That’s a sign that this is no longer a simple communication issue.

So it’s absolutely reasonable to speak to someone about how this is affecting you
You’re not asking for anyone to be punished. You’re asking for support in dealing with a situation that is impacting your work and mental health. That is exactly what HR or a manager is there for.
When you speak to them, keep it factual and make sure it is a pattern of behaviour that needs addressing. Talk to them (your line manager - ask for a formal meeting) talk to them about specific examples of snappiness or undermining
The difference in how she speaks to you vs others - don’t speculate why she does just keep it factual she does
The impact on your ability to do your job
The fact that you now avoid being alone with her as you feel uncomfortable, anxious and bullied and the constant snapping is effecting you negatively at work
Discuss the escalation since you raised concerns and that you have tried to help and support her and create a positive working environment

keep a log of what is said in the meeting and any outcomes agreed

met many of these older bullying type of women through work and then can be nasty…..