Trusts: Don't understand what my tutor wrote about 3 certainties.

As you're at university and you have the benefit of tutors - you really should be bringing this up with her, in person or electronically. It's very silly to go running to the internet as a first resort. You really need an understanding with your Trusts tutor, and if there is a problem of communication or understanding, you need to clear it directly, not via TSR.

CR means Chief Rabbi, like in the question...

The objects are perfectly certain here, they are Sam's 'nieces and nephews', that is, the sons and daughters of his brothers and sisters. Can't get much more certain than that as you can draw up a complete list of the nieces and nephews. As your tutor says it's not really like relatives - someone who was a 2nd cousin twice removed might pop up and start claiming to be a relative, and the trustee may not be sure if they should be or not, but in this case it is impossible for someone to pop up and claim to be a 'niece or nephew' without the trustee immediately being sure whether they are one or not.

If you're still confused about that bit, suppose Sam had left all his money on trust for his son, Fred. That is obviously a very certain object, right? The fact that Fred is a 'relative', doesn't mean you need to start talking about relatives in general!

Here the Chief Rabbi has no power at all to 'ascertain the objects', so don't get confused with Tuck's settlement trust at all. The objects are fixed, and certain. The Chief Rabbi's power is to choose how to divide the trust fund between those objects (i.e. all the nieces and nephews). It's a discretionary trust.

'residue' just means 'everything in Sam's estate apart from the property needed to fulfil the previous clauses of his will'. It's always certain since all the other clauses of the will must have certainty of subject matter - and the subject matter of the residue is 'the entire property' (certain) minus 'that needed for other clauses' (certain)

Oh right, it's Chief Rabbi lol. Thanks...
I see...it's odd, residue isn't really mentioned in any of my books. There's only one pagaraph about it in Penner's.

It should crop up quite often in practice when you think about wills for a moment.

Suppose I was writing my will right now and I had exactly £100k to bequeath, and no other property. Then I wanted to leave £5k to Charity A, £5k to Charity B, and £90k to my girlfriend.

But I'm not likely to die at that very instant. I may die a month from now (I hope its rather more), when my assets have swelled to £101k. If my will was as above, there is no problem where to give the £100k, but the remaining £1k would go to my statutory next of kin, say my father. But now suppose I don't want to give anything to my father at all, I just want to give the £10k to charity and the 'rest' to my girlfriend. I have two options. Firstly, I could create a new will every time my property grows or shrinks by any amount, so that the total sum is used up.

Or, more sensibly, I could say that I leave £10k to charity, and the remainder to my girlfriend - that way if I have £100k the remainder is £90k, if I have £101k the remainder is £91k, etc, if I have £95k and a car the remainder is £85k and a car, and there is no reason to keep remaking a will every time. But in every case, the subject matter of the bequest to my GF will be sufficiently certain. It will be my whole estate, minus that £10k that I gave to charity.