To lower the goalposts for DS2?

[TheRealPerson]

I have two DS's who have different academic abilities. DS1 has always been a little above average whilst DS2 has always been slightly below average (although he is starting to catch up now).
Last year, DS1 was told he was capable of achieving level 5s on English, Maths and Science sats. I told him that if he DID achieve this, I would reward him (he would be rewarded for effort anyway but this would have been a little more special iyswim?).
Anyway I found out yesterday that he did it.

DS2 is now worrying that he won't be treated because he knows he'll never get 5s.

WIBU to lower his target and tell him if he achieves a level 4b in everthing (national average) I'll treat him in the same way? would it be unfair to DS1?

There is no point in telling him to get 5s, it's unrealistic.

Or aibu?

(p.s. I know the sats are not important, I'm just trying to show them that working hard has its rewards and to work towards goals etc).

[colditz]

tell him to aim for what his teacher has told him he must aim for, and you will reward him if he achieves this.

And that is fair.

To each what they need, from each what they can give.

[Poledra]

I like colditz's approach and agree that it is fair to reward hard work, regardless of the eventual grade.

My DH says that, as a child, he couldn't understand why his sister got praised for her reports and he got a talking-to when he got mostly As and she got Bs, Cs and sometimes Ds. Now, with the benefit of adult hindsight, he says it might be because his sister's reports read 'XX is a delight to teach, tries very hard and is a asset to the class' whereas his read 'Belgarath could do so much more if he applied himself and actively took part in the lessons'!

[pranma]

Poledra and Belgarath-I love David Eddings too
I would ask the teacher for a relistic target for ds2 and tell him that he will be rewarded if he acieves this or if you can see that he has tried his best to do so.