Numbers: Writing down mental maths

Still doing mental Maths, Oliver seem to have gotten the pattern of adding and subscribing by counting up or down, now, it's all settling nicely in his head.  He sometimes uses fingers to count with bigger numbers ( mine, when I offer ) but generally prefers to do it 'in his head'.

This is the first time I wrote down what he's doing during our number session, marking what he got right  and wrong.  He loved seeing that he's actually getting things 'ticked off' and now that's what we are going to do.