I picked up this idea from one of my favorite blogs Chasing Cheerios. Although I didn't have marbles, I did have Skittles, so I improvised. I managed to do 5 different number exercises with my little guy all in one sitting.
1. I numbered small pieces of paper 1-8 (I only had 8 Skittles) and placed them in the tray.
2. I had Eager to Help put the Skittles in ascending order and then return them to the bowl.
3. I then added a 1 in front of the numbers explaining that the numbers now change. I wrote 11-18 on a piece a paper distinguishing 11 and 12 from the remaining teen numbers. I put the numbers in the tray all mixed up. He had to put the Skittles in ascending order naming each number.
4. Now was the fun part. He could pick one Skittle at a time to eat if he said the right number underneath it.
5. After he finished eating, we dumped the numbers out and then he placed them on the number line.