Year 5 Teaching Sequence autumn M1 – Measuring lines, area and perimeter (four days) Prerequisites: Draw rectangles, and measure and calculate their perimeters; find the area of rectilinear shapes drawn on a square grid by counting squares (see Year 4 teaching sequence M5) Know multiplication and division facts for the 2, 3, 4, 5, 6, 9 and 10 times tables (see oral and mental starter bank M1) Overview of progression: Children draw a range of rectangles with a given perimeter, and multiply the length by the width to find their areas. They learn to find the areas of right-angled triangles and use this to help to find the area and perimeters of irregular polygons drawn on squared paper. They also find the perimeters of regular polygons by multiplying the length of one side by the number of sides. Square metres, kilometres and millimetres are discussed including when each would be appropriate and children are asked to estimate the areas and perimeters of simple shapes. Note that experience of activities in this sequence should help children to realise that area does not always increase with perimeter. Note that names of polygons are also revised in preparation for Teaching Sequence S1. Watch out for children who confuse the units of measurement for area and perimeter. This can occur because children count the squares around a shape in order to measure its perimeter, and so think perimeter is measured in square units. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y5 Maths TS_M1 – Aut – 4days Objectives: Draw lines to nearest centimetre and millimetre Measure lines to nearest millimetre and centimetre Measure and calculate the perimeter of regular and irregular polygons Use the formula for the area of a rectangle to calculate the rectangle’s area Whole class Group activities Paired/indiv practice Resources Draw a rectangle on the board with sides between 20 and 30cm long. How can we find the perimeter of this rectangle? Remind children that the perimeter is the distance round the outside of the shape. Take feedback, and measure each of the four sides to the nearest millimetre and add up the four distances using a calculator. Did I need to measure all four sides? Why not? What do we know about rectangles? Draw out that opposite sides are the same length, and so we only need to measure two sides. So if we know the length of two sides, how can we find the perimeter? Draw out that we can double the total of two sides (one longer and one shorter) as this will give us the total of the two shorter sides and the two longer sides. Show children a rectangle on square paper, e.g. 8 squares by 5 squares (preferably an IWB background so that the squares are large enough to be seen). What is the area of this rectangle? Group of 4-5 children Give a book to each child. Show children a book with a dust jacket. Remove the jacket and discuss how it is made and how children could make dust jackets for the books they have been given. What measurements will we need to make? Draw out that children need to measure the width of the front cover, the spine, the back cover, and add on an amount for each flap. They also need to measure the height of the book, and add on a few millimetres so that the dust jacket slightly overlaps the book. Give children large sheets of paper to make dust jackets. They should write the title and author’s name on both the front cover and the spine, and decorate the jacket. Afterwards cover the jackets with sticky backed plastic before placing the jacket round the book and securing the flaps to the Children draw as many rectangles as they can with a perimeter of 48cm on squared paper. They find the area of each, using a calculator where the sides do not measure a whole number of centimetres. Easier: Explain that a long and a short side will need to add up to 24cm. Harder: Say that each side is not a whole number of centimetres. Large sheets of paper Coloured pencils/felttipped pens Sticky-backed plastic Stapler and staples or sticky tape Rulers marked in cm and mm 5/6 books, including one with a dust jacket cm2 paper Rulers marked in cm and mm Calculators © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y5 Maths TS_M1 – Aut – 4days sections covering the front and back covers (with small staples or sticky tape). Easier: Children round measurements to the nearest half centimetre. Remind children that the area is the amount of surface covered by the shape. Draw out that we can count the number of squares covered by the rectangle. Do we need to count the number of square in each row? Why not? Discuss how we can find the number in one row and then multiply by the number of rows. If each square was one centimetre long, what would the length of this rectangle be? And what would be the width? Sketch a rectangle and label the sides as 7cm and 3cm. The sides don't really measure 7cm and 3cm, but if they did how many square centimetres would be inside this rectangle? How do you know? So if we are trying to measure the area of a rectangle not drawn on squared paper, how could we work out the area? Draw out that we can multiply the length by the breadth. What units of measure would we use? Remind children that the squares measuring 1cm by 1cm are called square centimetres, and written as cm2. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y5 Maths TS_M1 – Aut – 4days Go back to the original rectangle. How could we find the area of this rectangle? Show children how to enter the measurement of the sides in just centimetres into the calculator to find the area in square centimetres. Draw a ‘T’-shape on squared paper (preferably as an IWB background). Agree its area with your maths partner. Take feedback and discuss how children found the area. Draw out that they could count the number of squares, or they could divide the shape up into rectangles and find the area of each. For example they could divide the shape into two rectangles one measure 5 by 2, and the other 3 by 2, or into two 2 by 2 squares and a 5 by 2 rectangle. What is its perimeter? Draw the following shape: Group of 4-5 children Give children cm2 paper and ask them to draw at least two non-rectilinear shapes with an area of 18 cm2 each on a separate piece of cm2 paper. Try and make your shape look different from your neighbour’s. Measure the perimeter of each to the nearest millimetre. Put the shapes in order of perimeter. Challenge children to draw a shape with the same area but with a perimeter greater than that with the greatest perimeter, and also a shape with perimeter less the smallest perimeter. Easier: Children use whole squares. Harder: Say that the sides of shapes do not all measure a whole number of centimetres. Children find areas of letters drawn on squared paper, and measure their perimeters to the nearest millimetre. Easier: Children use a calculator to help to find the total perimeter. Harder: The letters include more diagonal lines and so the areas and perimeters are more difficult to work out. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. cm2 paper Activity sheets of compound shapes (see resources) NB: these sheets and those for the next two sessions are drawn to scale so that one centimetre square does in fact measure one centimetre. However, printing and photocopying may alter this slightly and you may need to enlarge/reduce a little to compensate. Y5 Maths TS_M1 – Aut – 4days Talk to your partner about how you could find the area of this shape. Take feedback, focusing on how children worked out the area of the partially covered squares. Annotate the letter to show how the pairs of incomplete squares each form half of a rectangle measuring 2 by 1, and so we can find their area. Alternatively children may see the smaller of the partial squares fitting with the larger to make one whole. How could we find its perimeter? Do you think the answer will be a whole number of centimetres? Draw out that children will need to use a ruler to measure one of the diagonal sides, but not both as they are the same. Draw a hexagon on a plain background: Label one of the sides 5cm and explain that this is a regular hexagon. What do we mean by Group of 4-5 children Give children cm2 paper. Talk to your partner about how you could draw a triangle with an area of 4cm2. Take feedback and draw out that they could draw a 2 by 4 rectangle and cut it in half diagonally to form a right-angled Children find the perimeter of regular polygons (see resources) using a calculator to help, and the perimeter and area of irregular polygons. Harder: Also challenge children to draw an irregular but symmetrical © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Activity sheet of polygons (see resources) Rulers marked in cm and mm Calculators Y5 Maths TS_M1 – Aut – 4days regular? Talk to your partner about how we could find the perimeter of this shape. Take feedback and draw out that although we could measure each side, as it is a regular hexagon we can just multiply 5cm by 6 to find the perimeter. What if it was an irregular hexagon? Repeat, this time drawing a regular pentagon with sides shown as 6cm 7mm. How could we enter this measurement into the calculator? Draw out that we could enter it as 6.7 or 67 depending on whether we want an answer in centimetres or millimetres. Enter 6.7 × 5 = to find the perimeter in centimetres. Draw the following right-angled triangle on squared paper: Talk to your partner about what might be the area of this triangle. Take feedback drawing out how children found the answer. Children may have seen two 2 by 1 rectangles sliced in half, or see the whole triangle as half of a 4 by 2 rectangle. Draw the following irregular hexagon on squared paper. triangle. (They could also draw an 8 by 1 rectangle.) Ask children to draw the triangle. hexagon with an area of 16cm2. Talk to your partner about how you could use this to help you to draw a triangle with an area of 8cm2. Sketch the following triangles: Which of these two triangles do you think will have the greatest perimeter? Why? Ask children to work in pairs to draw at least three triangles with an area of 6cm2 and to find their perimeters. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y5 Maths TS_M1 – Aut – 4days How could we find the perimeter of this shape? Discuss how two sides are two units long, and four are the same number of units long and would need to be measured. How could we find the area? Talk to your partner about what you think the area might be. Take feedback asking children to explain how they arrived at their answer. Draw out that there are 12 whole squares, and three squares are cut in half, four times, so four lots of 1½ squares, making another 6 squares, so the total area is 18 square units in total. If our hall was having a new floor and the price was worked out based on its area, how do you think we could work out the area? Would we measure it in square centimetres? Agree that it would be more likely to measure the hall’s length and width in metres, and so the area would be measured in square metres. If the hall is free, go and do this. If not, measure it in advance and display the measurements, explaining that you rounded up to the nearest metre. So what is the area of the floor? How Easier: Children may find it easier to cut out several copies of the first triangle and stick them together to form new triangles. Harder: Challenge children to draw at least two other triangles with an area of 8cm2 and six other triangles with an area of 6cm2. Group of 4-5 children Draw round a leaf on cm2 paper. Together estimate its surface area, agree how to include partially covered squares, for example pairing them up to make a whole square, or rounding the area of each partially covered square to the nearest half square. Use a piece of string to help find the perimeter. Show children a range of leaves. Which Children estimate which shapes have the greatest and least perimeter and which have the greatest and least area (see resources). They record their guesses and then measure to find out. They then estimate and measure the area and perimeter of four rectangles, using calculators where necessary. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Five or six leaves of different perimeters and areas String cm2 paper Activity sheet of shapes (see resources) Calculators Y5 Maths TS_M1 – Aut – 4days do you think this would be written? Show children how square metres are written. How many square centimetres do you think might be in a square metre? If we had a square, one metre by one metre, what would be the length of each side be in centimetres? And what is 100 multiplied by 100? Agree that one square metre is 10,000cm2. How do you think the area of our playground might compare with the hall floor area? Twice as much? Three times? When might we use measure area using square millimetres? Take a range of suggestions. How many square millimetres do you think there are in one square centimetre? Talk to you partner about how you could work it out. Agree that one square centimetre is 100mm2. What might we measure in square kilometres? Take a range of suggestions. Talk to your partner about how many square metres there are in a square kilometre. Agee that there are a million square metres in a square kilometre. Write the following areas on the board: 12m2, 120m2, 12cm2, 28cm2, 12mm2, 28mm2 Which of these do you think could be the area of a bedroom floor? The surface area of a little finger nail? One side of a credit card? of these do you think have a greater surface area than the first leaf? Ask children to make an estimate of the area for each leaf, based on their experience of the first. Repeat, this time find the perimeter of the first leaf, and then predicting which leaves will have a greater perimeter. Give a leaf to each child and ask them to draw round it on squared paper to find its approximate area, and to use a piece of string to help find its perimeter. Compare the result with children's estimates. Easier:/Harder: Children’s approximations will vary in accuracy according to how they are able to take partial squares into account. Harder: Ask children to work in pairs to agree an order of the shapes first according to size of area and then according to size of perimeter, before measuring them. Children's estimates of perimeter are likely to be more accurate. © Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Rulers marked in cm and mm Y5 Maths TS_M1 – Aut – 4days