Not a tip, but if you want to continue at teaching, looking into a train the trainer course, they are short but give great guidance on the best way to get your knowledge across

I'm the last person to be giving advise on this, but someone said before to repeat the last part of the sentence the other person just said and I realised that a friend of my does this and he does have great social skills. It's meant to confirm that to the other person that you were listening and taking in what they were talking about, there is probably a bit of skill involved in what to repeat otherwise it could come off as condescending or dismissive

It's due to the tilt of the earth's axis, the further north the shorter the days in winter but longer in summer. So London has a shorter winter day than californa but longer summers day

The "system" is just whatever policy the company has in place, obviously most companies want the employees to use up their leave every year as otherwise it could mean many staff looking for months or more off together. My own company will only allow 35 hours to be carried over but that policy only came in in 2000 and I member of staff who started on the old policy currently has 1600 hours carried over

Haha, gravy is actually clear(ish) when made from scratch, Google "gravy browning liquid"

If you live in the kind of building that cuts keys for contractors and just lets them walk away to use them, then the building management is the problem, not the keys.