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Addition and Subtraction Unit 1Whole Class Teaching Input DAY 1Objectives Add pairs of 2-digit numbers mentally. Add 2–digit numbers to 3-digit numbers using mental strategies.Resources‘2-digit + 2-digit grid with missing totals’ (see resources)TeachingShow the 2-digit + 2-digit grid with missing totals (see resources).Model adding two of the numbers on the grid using partitioning into 10s and 1s. Add the 10s together first, and then the 1s. Finally add them both to find the total. For example, 24 + 48. First partition into 10s and 1s: 20 and 4, 40 and 8. Add the 10s: 20 + 40 = 60. Add the 1s: 4 + 8 = 12. Add them together to find the total: 60 + 12 = 72, so 24 + 48 = 72Write 137 + 19, 178 + 31, 125 + 26, 154 + 27 and 22 + 195 on the board. Discuss how to do each one, mentally with a jotting if necessary. Point out that for the first one, it is better to add 20 to 137 first and then adjust by subtracting 1. Agree to use partitioning for all the rest. Group activity notes DAY 1 Use the in-depth problem-solving investigation for this unit – Make 100 – as today’s group activity, or use the activities below.Create and add 3-digit and 2-digit numbers, investigating finding totals with different criteria.Objectives: Add pairs of 2-digit numbers, mentally with jottings. Add 2-digit numbers to 3-digit numbers, mentally with jottings.You will need: 1–9 dice or 1–9 digit cards, ‘Adding 3-digit and 2-digit numbers’ (see resources)Groups of 6 – with T or TA Working towards ARE / Working at ARE / Greater DepthShare the investigation, adding 3-digit and 2-digit numbers (see resources). Children roll a 1–9 dice five times (or pick five cards from a set of 1–9 digit cards). Using the 5 digits, they generate 3-digit + 2-digit number sentences which give: the smallest total possible, the biggest total possible, an even number, an odd number, a number which has at least one digit 2 times. Ask: What rules do you need to follow to make these totals? Children check a partner’s answers and test their own rules with other sets of 5 digits. Sit with different groups in turn. Help children to explore the questions fully, checking they have definitely found the biggest and smallest numbers possible. Help them to write down some rules/instructions which would help other children complete the task.Outcomes: I can make additions with 3-digit and 2-digit numbers, finding the biggest and smallest possible totals.Whole Class Teaching Input DAY 2Objectives Add two 3-digit numbers using compact written addition. ResourcesWhiteboardsTeachingDisplay 324 + 439 and ask children to use the written method to find the answer on their whiteboards. Note and share different strategies and explain that we are going to focus on compact written addition. Model this: 324 + 439_1_ 763Emphasise leaving a space ABOVE the line in case we have to write 10s digits when adding the 1s or 100s digits when adding the 10s. Writing them above the line will mean we don’t forget to add them in. Model the addition, talking it through from right to left.Group activity notes DAY 2 Group activity notes DAY 2Add pairs of 3-digit numbers using compact written addition.Add pairs of 3-digit numbers using compact written addition.Objectives: Add two 3-digit numbers using compact written addition. Objectives: Add two 3-digit numbers using compact written addition.You will need:You will need: ‘Special magic squares’ (see resources), calculators Groups of 6 – with T or TA Working at ARE / Working towards AREWrite 243 + 675 and ask children to use compact written addition to find the answer. Give support to less able children who may need to use the expanded method, like this: 200 40 3+ 600 70 5 100_______________ 900 + 10 + 8 = 918Next, write 337 + 339 and ask children to ‘think, pair and share’ how to calculate the answer. Model using compact addition. Explain that as 7 + 9 is 16, the 1 needs to go above the line in the 10s column. It is then added to the 10s. Repeat with 271 + 384 and 347 + 458.Ask more able children to model how they would work the first of these out. (This time children will have a 100 from the 10s to be added to the 100s.)Working towards ARE: Support with place value equipment as well. Pairs or individually – with TA or independently Working at ARE/Greater DepthGive each child/pair a Special Magic Square sheet. Ask children to use compact written addition to add the numbers in each row, each column and each diagonal. They can share these between them but must do at least five additions each! What do they discover? Repeat with the second magic square.Now look at the little square at the bottom. There is a connection between this little square and the first big square. The key number for the square is 43… Use a calculator to find that connection! ChallengeCan they find the key number for the second square? Outcomes: I can use compact written addition to add two 3-digit numbers.Outcomes: I can use compact written addition to add two 3-digit numbers.Whole Class Teaching Input DAY 3Objectives Add three 3-digit numbers using compact written addition. ResourcesWhiteboardsTeachingDisplay 592 + 235 on the board. Ask children to use compact written addition to solve this on their whiteboards. Discuss the answer and clarify any mistakes. Explain that we can also use this strategy to add three 3-digit numbers. Display this calculation with three 3-digit numbers on the board: 123 474+ 332_____ _____Ask children to calculate the total. In this example we move a digit from the tens to the hundreds. Agree that the total is 929 then ask children to find the total of 238 + 111 + 216.Check that they lay out their work correctly, with the 1s, 10s and 100s lined up and a space before the line at the bottom.Agree that the total is 565. Group activity notes DAY 3 Group activity notes DAY 3Create and add three 3-digit numbers using compact written additions.Use compact written addition to add three 3-digit numbers with ‘carries’ in different columns.Objectives: Add three 3-digit numbers using compact written addition. Objectives: Add 3-digit numbers using compact written addition. You will need: 0–9 digit cards, place value cardsYou will need: Groups of 3 – with T or TA Working at ARE / Working towards AREWorking in groups of 3, children generate three 3-digit numbers using 0–9 digit cards. They record their three numbers then add them using compact written addition.Less able children can start by using expanded addition.Support children by using place value cards to help them make a physical representation of the expanded addition.Children can then record and solve the calculation using the compact written method.Groups of 6 – with T or TA Greater Depth First, ask children to choose three 3-digit numbers and demonstrate that they can use compact addition to add them.Then challenge children to make up four more of their own additions of three 3-digit numbers.Their first addition must require them to carry from the 1s column (ensure children understand what is meant by ‘carry’ in this context before using this vocabulary).Their second addition must require them to ‘carry’ from the 10s column.Their third addition must require them to ‘carry’ from the 100s column.Their fourth addition must require them to ‘carry’ from two columns.They should then make up harder additions where they add three or four 3-digit numbers! Outcomes: I can make and add three 3-digit numbers using compact addition.Outcomes: I can add three 3-digit numbers and show how to ‘carry’ the 1s, 10s and 100s.ADDITIONAL RESOURCES‘2-digit + 2-digit grid with missing totals’ (see resources)1–9 dice or 1–9 digit cards ‘Adding 3-digit and 2-digit numbers’ (see resources)Whiteboards‘Special magic squares’ (see resources)Calculators 0–9 digit cardsPlace value cardsThe links to the websites and the contents of the web pages associated with such links specified on this list (hereafter collectively referred to as the ‘Links’) have been checked by Hamilton Trust (being the operating name of the registered charity, William Rowan Hamilton Trust) and to the best of Hamilton Trust’s knowledge, are correct and accurate at the time of publication. Notwithstanding the foregoing or any other terms and conditions on the Hamilton Trust website, you acknowledge that Hamilton Trust has no control over such Links and indeed, the owners of such Links may have?removed such Links, changed such Links and/or contents associated with such Links. Therefore, it is your sole responsibility to verify any of the Links which you wish you use. Hamilton Trust excludes all responsibility and liability for any loss or damage arising from the use of any Links. ................
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