Hope someone can help me with this one.
DS's homework (year 3) this weekend was a sheet of double digit addition, eg, 39+61= and variations on this eg ?+69=84. I have no idea whether this was supposed to be done as a mental maths exercise or numberlines or what. He has already had a 'numberlines' homework, so not sure it was testing that. He did the questions mentally and was fairly good at them but would, on occasion, forget to add units or would sometimes have trouble holding it all in his head when 'bridging through' a 10s number. He would, say, know that he had to bounce down 6 to get to the 10s number but would lose his tread when trying to remember how many more to bounce down if, say, he was supposed to bounce down 9 in total, ie, on 56, bounce down 6 to get to 50 and then should bounce down another 3 to have subtracted 9 altogether.
God! Hope I've made sense with all that! My question is, should the average/ above-average year 3s be doing that kind of sum mentally yet, or are they still in the practising stage for that kind of question? Don't know whether to really focus on those kind of sums with him for a while, or whether to keep going through our multi-topiced maths workbook. He got a level 3 in the end of KS1 SATS but maths is not his strongest subject and I want to iron out any glitches before we hit 11+ territory.
Sorry, very long-winded post for simple question