Then ask one student to take the counters out of the container and put one on each small circle of a place value board. A place value board has 10 small circles in one section for the ones, ten larger circles for the tens. If you make the circles the same size as the bottom of a bathroom paper cup, you can use those to hold ten of any item you are counting. In the next section have circles large enough for a bowl or coffee can. This container needs to be large enough to hold ten of the bathroom cups, or 100 items per circle.
Once all the circles on the ones section are filled then have your student take them off the ones circles and put them in a bathroom cup and put the cup on the tens side.
For this example, Quentin filled the ones section twice and had three frogs left over. It was easy for them to see that there were 23 in the jar. This is a pleasureable way to learn estimating skills if you do this regularly with different counters and different containers of all sorts of shapes and sizes.
After you have done this several times, you can increase the amount of counters you are usings as well. Initially their estimates will not be so accurate this time, as the numbers you work with are higher. Give your students chances to change their estimates as they go along because the object is for them to get better at estimating, not winning against each other. Once you have completed your estimating exercise and are ready to hand out the counters for a snack, first have them figure out the quickest and easiest way to divide the crackers equally.
For the benefit of Sam and James, I followed along with on the white board, writing down everything they did. In the end Quentin said, "That sure is a lot of numbers!"