This program shows one jar filled with marbles and gives the exact amount. The second jar is filled with a different amount and number is not shown. Students can compare the jars to estimate how many are in the second one. Again this is best used projected on a screen from a computer. There are three difficulty levels.
We homeschool our daughter and I teach her the math portion of her day. We were going over a lesson on estimation and I thought something like this would be a good visual to practice estimating.