When teaching addition to my pre-k students, I get a piece of coloured paper and draw a line down the middle. On the left-hand side of the line, I put a dot or a star.
I give each of the children some counters (bears, bugs, spiders, bats, erasers, etc.) up to 10. I show them a number card (e.g. 4) and tell them to put that many counters on the side with the dot / star.
Then, I put the + sign card down and show them another number card (e.g. 2). They then put that many counters on the other side of the line. Then I put the = card down.
Next, I ask them to count all the counters together. I ask ‘What does four add two equal?’ They can tell me 6 because 4 on one side and 2 on the other is 6 altogether.