I have found some apps that are great for problem solving which have provided some really engaging and stimulating lessons where the children have been able to develop key thinking skills to help them with their Numeracy.
Working from the National Strategies guidance the three areas of problem solving are identified as:
Banana Maths - Is a great app for introducing word problems to KS1children. The app uses pictures to substitute words so that children can focus more on the specific vocabulary that helps them work out the calculation needed to solve the problem. CLICK HERE TO SEE HOW WE USED THIS IN CLASS. Another app similar to this is Problem Solving: Choosing the correct operation. This app would be aimed more older and again helps children decode a question to work out the number sentence needed to solve a problem.