Price $0.99 and worth every penny!
In this app, there is a picture of a large tree with a set of french doors. The doors open up to reveal an object for a short period of time for students to subitize. Then the doors close and the student has to touch the number that they saw when the door was open. It is very easy to customize depending on the level your students are at. You can easily change the amount of time the door stays open, the range of the numbers.
There are also many different representations you can switch between. There are dominoes, playing cards, random animals, dice, ten frames, hands, bead strings and 2 color counters.
This is a great app to build number sense and additive reasoning.
Ten Frame Fill
In this app, a ten frame gets filled up with some counters and you are asked to figure out how many more counters you need to make 10. There are counters of another color that you can pick up and drag into place if you need to or you can simply touch the number across the bottom if you know the correct response. The options page lets you chose which equations to display as well as how you want the 10 frame to fill.
I have been using this app a lot in grade 1 over the last month. I like to sit with a kid and ask them how many they see and how many more they need to make 10. We also talk abut the different equations we could write to represent the situation. It has really helped my students work on subitizing, addition, subtraction and the all important combinations of 10.