Year 2 key objective Understand that subtraction is the inverse of addition; state the subtraction corresponding to a given addition and vice versa Associated knowledge and Errors and Questions to identify errors Teaching to address errors and Next steps skills misconceptions and misconceptions misconceptions Count on and back in ones Makes mistakes when Choose a teen number and Use a number line and a 100-square to Use known facts about adding and and tens. counting using teen count backwards from your count forwards and backwards in ones and subtracting ten to work out how to 1 Y2 +/numbers and/or crossing number in ones. What is the tens. calculate using nine and eleven. boundaries. next number, the number before? Encourage similar counting activities using a visualised number line. Count forwards in tens from 7. What number is ten more than 27? ... ten less than 97? Identify pairs of numbers Has difficulty in What is 3 + 5? Use rulers and number squares to support Extend patterns to numbers beyond What is 13 + 5? practice with recall of number pairs 20; that add to twenty and use remembering number pairs totalling between How did you work that out? beyond ten and emphasise patterns in use 4 + 3 = 7 to deduce other known number facts to ten and twenty, resulting number pairs. number facts such as 14 + 3 = 4 + 13 add mentally. in calculation errors. Which pair of numbers adds and so on. to 18? Y2 +/Are there any other pairs? Find a difference by Counts up unreliably; still How many do I add on to get Use a number line to demonstrate Ask the child to choose a new jump counting up from the counting the smaller from three to eight? counting up by jumping in ones and size, for example twos or fives, to smaller to the larger number to get one too highlighting the equivalent larger jump. find the difference between two number. many in the answer. I've got three sherbet dips This will illustrate that the starting number given numbers. How can you check 3 Y2 +/and I want eight. How many position is not included in the jump. your answer? do I need to buy? Recognise subtraction as Does not relate finding a What is the difference Illustrate the connections between Provide the following three taking away, finding the difference and between 21 and 18? different aspects of subtraction using a questions: difference and complementary addition How did you work it out? range of models and images, such as complementary addition. to the operation of What operation did you use? number lines, money, counters or What is the difference between 4 Y2 +/subtraction. Interactive Teaching Programs (ITPs) such 21 and 18? What other ways can you as Counting on and back, Differences, 21 - 18 = ? think of for subtracting 18 Number facts. 18 + [_]= 21? from 21? What do you notice about these and their answers? Make up some of your own and explain the patterns you are using.
Recognise, for example, that subtracting 13 'undoes' adding 13 and vice versa, and that this means that since 4 + 13 = 17, we can state the inverse that 17 - 13 = 4. 5 Y2 +/-
Is insecure in making links between addition and subtraction and/or recognising inverses.
Develop and recognise patterns to help deduce other addition and subtraction facts. 6 Y2 +/-
Does not readily use number patterns to support calculating, for example: 46 - 5 = 41, so 46 - 15 = 31, 46 - 25 = 21, etc.
What is the answer to 30 add 20? If 30 add 20 is 50, what is 50 subtract 20? What is 17 subtract 8? Write a number sentence for this calculation. Use the three numbers to write an addition fact. What is 14 + 5? ... 14 + 15? ... 14 + 25? Using this information, tell me what 24 + 25 is What is 6 - 4? ... 16 - 4? ... 26 - 4? Now what do you think the answer is to 56 - 4? How did you work that out?
Use digit cards and number lines to make and check number statements that involve inverse pairs such as 11 + 3 = 14, 14 - 3 = 11
Use number squares to demonstrate and highlight patterns such as 5 + 1 = 6, 15 + 1 = 16, 25 + 1 = 26 32 - 2 = 30, 32 - 12 = 20 getting children to predict and check other cases.
Give the child statements to sort into pairs involving inverses, then into groups that make up a set of the four equivalent statements such as 24 + 3 = 27, 3 + 24 = 27 27 - 3 = 24, 27 - 24 = 3 Invite the child to make sets of equivalent statements using numbers they have chosen. Extend to include patterns where the calculations cross a boundary such as 14 + 9 = 23, 14 + 19 = 33 56 - 9 = 47, 56 - 19 = 37