ac9vity*process review, ac9vity*process guessmate? acmna099 · ac9vity*process es%mate!...
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Australian Curriculum Year 5 ACMNA099 Use es%ma%on and rounding to check the reasonableness of answers to calcula%ons Key Idea • In our everyday lives we constantly use
es%ma%on and rounding. We don’t always need the exact or correct answer.
• Learners use green fish thinking, with es%ma%on and rounding strategies, to check the reasonableness of answers.
Vocabulary about, roughly, educated guess, good guess, gues%mate, close to, thereabouts, something like, not far from, more or less, is near enough to, approximately. es%mate, nearest to, round to, quan%ty, Resources FISH problem solving kit (especially green fish) Maths learning journals Various items for es%ma%on eg paperclips Large jar filled with jelly beans ( or similar) ‘Great Es%ma%ons’ by Bruce Goldstone Flash Cards
Ac9vity Process-‐Review This ac%vity looks at finding out what students know about es%ma%on and where they use it. 1. Move students into small groups. Students brainstorm places/ideas/events/things where and why an exact answer is not needed. By rounding or es%ma%on, an answer closest to the correct answer is good enough. • Examples: bill at a restaurant, length of the oval, how
many people in a football stadium crowd, words on a page, books in a box, product that is the best value, cars in a carpark, students in a classroom, pencils in a pencil case, height of a desk
2. In Mathema%cs, we oUen focus on geVng an exact answer. But in everyday life, for example when shopping. Most people think a few cents here or there are not going to make much of a difference when adding the total amount spent, rather we need to focus on the dollars • Use shopping dockets and using a calculator add the
amounts together. Discuss what a few cents came to over the total amount.
3. Es%ma%on is…finding a number that is close enough to the right answer you are not trying to get the exact answer what you want is something that is good enough (usually in a hurry) Rounding is reducing the digits in a number while trying to keep its value similar. The result is less accurate but simpler to use. 4. Students write their own defini%ons of what es%ma%on
and rounding are and where they may be used or useful, in their student learning journals.
Ac9vity Process-‐Guess0mate? This ac%vity is about making a reasonable guess using a silent conversa%on strategy. Green fish need to be displayed. Set out a number of groups of objects e.g. a cup of paper-‐clips, a pile of books. Around the classroom. Asked the students to walk around silently and es%mate/guess e.g how many paper-‐clips in the cup etc They record their es%ma%ons, Eg. 100 The exact numbers are then revealed and students look at whether their guess was too many, near enough, or not enough etc. Students will be encouraged to use a suitable descriptor from the vocab list to apply to their guess. My answer was reasonable because………… Students record in their journals a strategy they use to es%mate and shares this with another student in a think, pair, share ac%vity. This ac%vity can also be extended to es%mate measurements (length, volume, capacity), as well as quan%ty.
Ac9vity Process-‐Es%mate Ask students to es%mate the following: 610 + 485 and expain their method if es%ma%on using Yellow Fish thinking. Ac9vity Process-‐Group words Animals like ourselves oUen live in communi%es. A collec%ve noun is used to describe a large number of animals congregate together. Eg a colony of bats. And some of these words are unusual eg. murder of crows. • Working in small groups. Ask students to look at an
image of a penguin colony and es%mate the number of birds
• Ask them to use a transparent grid to develop an answer
• Ask students to use green fish thinking to jus%fy the reasonableness of their es%ma%on
Ac9vity Process-‐Rounding and es0ma0ng whole numbers using place value Numbers can be rounded to the nearest 1 or 5 or 10 or 100 or 1000 depending on the context. h?p://www.learnalberta.ca/content/me5l/html/math5.html Uluru which is a very well known Australian icon, originally sat at the bofom of a sea, but today stands 348m above ground, with some 2.5kms of its bulk underground. Uluru lies west of the Simpson Desert, not far from the ‘Red Centre’ of Australia, about 335kms southwest of Alice Springs (as the crow flies) and 463kms by road. Round 348 to the nearest hundred 300 350 400 Discuss with class the op%ons for rounding and difference in the answer if it is rounded to the nearest 10. Also discuss why an understanding of rounding is basic to developing effec%ve es%ma%on skills Ac9vity Process-‐Rounding Use an three empty number line ask students to place the following numbers in their correct posi%on. 335, 463, 685. Round each number to the nearest ten and then use es%ma%on to find the sum of the three numbers. Are the es%mates close the the actual answer?
Extension Ac9vity Process-‐Visual Es%ma%ons Ask students to pose es%ma%on ques%ons based on crea%ve commons images Sites which have crea%ve commons images that teachers could find images to be used hfp://www.pics4learning.com/ hfp://flickrcc.bluemountains.net/flickrCC/index.php hfp://www.fotopedia.com/search
and locate them on number lines. They add and subtract frac%ons with the same denominator. Students con%nue paferns by adding and subtrac%ng frac%ons and decimals. They find unknown quan%%es in number sentences. They use appropriate units of measurement for length, area, volume, capacity and mass, and calculate perimeter and area of rectangles. They convert between 12 and 24 hour %me. Students use a grid reference system to locate landmarks. They measure and construct different angles. Students list outcomes of chance experiments with equally likely outcomes and assign probabili%es between 0 and 1. Students pose ques%ons to gather data, and construct data displays appropriate for the data. Background Es%ma%on is a skill for life. It is an important part of mathema%cs and a very handy tool for everyday life. Students need to get in the habit of es%ma%ng amounts of money, lengths of %me, distances, and many other physical quan%%es. Students need to understanding that rounding means reducing the digits in a number while trying to keep its value similar. The result is less accurate, but easier to use. Example: 73 rounded to the nearest ten is 70, because 73 is closer to 70 than to 80. It is a common rule that when rounding • 0,1,2,3 and 4 are on team "down" • 5,6,7,8 and 9 are on team "up"
Digital Learning h?p://www.learnalberta.ca/content/me5l/html/math5.html Games involving es0ma0on h?p://www.mathsisfun.com/numbers/es0ma0on-‐game.php Teacher will need to specify topic for students. Some topics are above the year 5 expecta%ons. Brain Pop VIdeo (includes teacher notes) h?p://www.brainpopjr.com/math/numbersense/rounding/grownups.weml Inves9ga9on:-‐How many jelly beans? 1. Show students a large jar filled with jelly beans. 2. Get students to examine the jar and determine about how many jelly beans are inside. 3. Students are to record their es%ma%ons and working out on s%cky notes. S%cky notes are then stuck onto a large poster so that all answers can be viewed. 4. Students share what they answered, no%ng the
range of answers. 5. Discuss how students decided on their answers. 6. Dis%nguish between es%ma%ng and guessing. (Es$mates involve strategies.) Key Ques%on: Is it okay to make an es9mate? Discuss -‐ Are we looking at an es%mate or an exact answer? Is it important? Students write responses to ques%on in their Maths’ Learning Journal using examples to support there response Assessment-‐Student Learning Journal The learning journal is used throughout this MAG to get students to think about and reinforce what is being taught. It is hoped that the concept will be befer understood, when students describe their understanding in their own language rather than formal ‘teacher talk’. Assessment Year 5, students solve simple problems involving the four opera9ons using a range of strategies. They check the reasonableness of answers using es9ma9on and rounding. Students iden%fy and describe factors and mul%ples They explain plans for simple budgets. Students connect three-‐dimensional objects with their two-‐dimensional representa%ons. They describe transforma%ons of two-‐dimensional shapes and iden%fy line and rota%onal symmetry Students compare and interpret different data sets. Students order decimals and unit frac%ons .