I would like to propose the following activity (also known as neighbours numbers):
the activity outputs two consecutive numbers and the user should enter the following one
The activity would have different set of level:
- find the following one
- find the previous one
- find the one between two
- find the previous and the next one
- can be first between 0 and 10, then 0 to 20.
Some help could be added, like showing the numbers between 0 to 10/0 to 20 depending on the actual level. Another level of help could be that the number of the question is highlighted in the help.
As options, the help can be disabled. Of course, levels type can be chosen individually, to practice specific knowledge (as in algebra_***).