The latest draft version of the Primary Maths Programme of Study includes counting to and across 100, which has usually been left until year 2. It is quite tricky and shouldn’t be covered until you are certain that children can count confidently up to 100.
Here is a worksheet aimed at helping with this, counting three, four or five more in steps of one and crossing the hundred boundary in each case. Thanks to urbrainy.com for letting me adapt one of their pages.