Hi - retired TA (male) here :
I think it is important for a child to be able to visualize what is happening when they learn bonds of ten.
So, yes an abacus is good. Possibly more fun is Lego bricks, counters, or some other small items that you have at least ten of.
Draw a centre-line and place the ten items in a vertical line to the left of the centre-line. On another piece of paper ask DD to write, in numbers, what she can see: ie, 10 one side, 0 the other side : 10 + 0.
Now get her to take one item across to the other side, and (ideally WITHOUT COUNTING) say how many are left, then write the sum ('number picture' some schools call them), ie, 9 one side, 1 the other side : 9 + 1.
Now take another item across, and do the same thing: ie 8 + 2.
(I'm sure you get the idea, so I don't need to go through the whole lot ! )
However, do observe two points: when it gets to 5 + 5 the two sides are EQUAL, and as it continues the, left hand side gets less, while the right hand side increases until, visually, the two sides have swapped places from where they started.
(Sorry this has been a very long-winded explanation of something, that once it is grasped, is self-evident, but I always think it important for a child to see and understand what is happening, and NOT just learn things by rote, without understanding WHY.)
A Year 6 girl came to me once, saying she never understood 'Taking
Away' in Year 2, until I explained it to her : "Imagine you have three sweets in your hand; a robber comes and steals two of them - he takes them away. How many are left?" And she could do that in her head. [The most surprising thing for me was that she still recalled the incident four years later!] ('Take Away' to a child could mean where Dad gets the 'Chinese' on a Friday evening!)
It surprises me DD got to Year 3 without this having been picked up by school, that she didn't know her bonds. Maybe a tactful word with teacher might throw some light on how this was overlooked, and are other children in a similar position.