Select, use and record a variety of mental strategies to solve addition and subtraction problems, including word problems, with numbers of up to four digits

 1 Changing Numbers: 324 to 314 2 Changing Numbers: 562 to 662 3 Changing Numbers: 500 to 510 4 Changing Numbers: 444 to 445 5 Same or different? Click all boxes with answer 18 6 Same or Different? Click all boxes with answer 16 7 Addition Chains 8 Addition Chains 9 Addition Chains 10 Addition Chains 11 Addition Chains 12 Number Detectives: 24 + 6 = ? 13 Number Detectives: 5 + 25 = ? 14 Addition Chains: 4 + 5 + 6 + 8, 11 + 4 + 3+ 7 15 Number detectives: 22+9 = ? 16 Number detectives: 51+11 = ? 17 Spot the difference between 30 and 15. 18 Spot the difference between 12 and 25. 19 Spot the difference between 30 and 10. 20 Spot the difference between 40 and 10. 21 Spot the difference between 20 and 39. 22 Spot the difference between 18 and 25. 23 Spot the difference between 25 and 34. 24 Spot the difference between 19 and 31. 25 Spot the difference between 19 and 42. 26 Spot the difference between 36 and 15. 27 Spot the difference: 60 & 40, 12 & 18, 100 & 95 28 Spot the difference: 20 & 14, 17 & 9, 80 & 73 29 Spot the difference: 100 & 30, 19 & 11, 30 & 24 30 Spot the difference: 50 & 41, 100 & 92, 101 & 98 31 Big Brother? - working backwards 32 The Busy Bus - students on and off bus 33 Dr Dan's Number Operations - "x + 2 = 10" 34 Who's going to Waterworld? 2+3+3+10