I helped a friend yesterday with some ideas for teaching her son the combinations that make ten. Apart from using ten frames to visualise these combinations the idea of "friends of ten' is a good one. It helps for students to know these instantly - 1 and 9, 2 and 8, 3 and 7, 4 and 6, 5 and 5, 6 and 4, 7 and 3, 8 and 2, 9 and 1.
Use connecting cubes is a great way to first introduce this concept, as you can 'build' the combination and then flip it around to show the reverse is true (so in the example below 2 and 8 and 8 and 2 can be seen by simply reversing the stick of cubes).
Here is a little way of helping your student to BUILD their understanding using some hands-on equipment. I used 2 yoghurt cups that had not been split apart. Encourage your student to count with each 'drop' of the cube into the cup. This will help with 1:1 correspondence.
I have just sent my Premium Club members their graphics for today, some 'finger counting hands' that will be great for maths activities and worksheets.