compare, estimate, and determine measurements in various contexts
explain the relationships between grams and kilograms as metric units of mass, and between litres and millilitres as metric units of capacity, and use benchmarks for these units to estimate mass and capacity
Show students a balance scale with markings for grams and kilograms. Provide them with various items to measure in grams using the scale. Have them identify benchmark items for 25 g, 50 g, and 500 g. Have them predict how many of these benchmark items would be needed for 1 kg, then measure to verify their predictions. Through this task, support students in developing an understanding that 1000 g is equivalent to 1 kg.
As a home connection, encourage students to visit a grocery store to find fruits and vegetables of different masses, and use these to create personal benchmarks. Have them use their benchmarks to estimate whether a mass is closer to 500 g, 1 kg, 5 kg, or 10 kg and measure to confirm their prediction. Support students in recognizing that the relationship between grams and millilitres is also helpful in developing benchmarks.
Have students use metric measuring cups, measuring scoops, beakers, and graduated cylinders to measure the capacity of containers using millilitres; a combination of litres and millilitres; and litres only, rounding the capacity to the nearest whole litre. (Note: In Grade 4, it is not an expectation for students to write with decimals to thousandths, so they could express the measure by saying 1 L plus 250 mL, or a little more than 1 L, and so on.) Have them find objects with benchmark capacities (1 L, 500 mL, 10 mL, and 1 mL) and use these to estimate. Have them use the relationship between a centicube and 1 mL to connect the size of the place-value blocks to their capacity (e.g., the thousands cube could hold 1 L of liquid).
Show students that 1 cup is approximately 250 mL (benchmark). Confirm that 4 cups is approximately 1000 mL or 1 L. Provide them with various items that have capacities from 50 mL to 4 L. Ask students to use these benchmarks to establish other benchmark measures, then use them to estimate and measure.
use metric prefixes to describe the relative size of different metric units, and choose appropriate units and tools to measure length, mass, and capacity
The metric system continues beyond the chart above, in both directions, to describe even larger and smaller amounts. This is covered in Grade 8.
Show students the metric prefixes from kilo- to milli- and discuss the relationship between them and the place-value system. Ask students to share their experiences with measuring using other types of units (e.g., a horse is typically measured in hands; diamonds are measured in carats).
Have students bring products or pictures of products from home that have labels with capacity, mass, or length dimensions (e.g., a 325 mL mustard container; 454 g of butter; a 1.8 kg bag of dried cranberries; 7.62 m of aluminum foil). Have them think about the relationships between different metric units and pose questions related to the measures (e.g., “I have 1 L of mustard. About how many 325 mL containers can I fill?”; “I have 1.8 kg of cranberries. How many 100 g bags of cranberries can I fill?”).
To foster an appreciation of different perspectives from around the world, have students share places where they have been, have lived, or come from that use metric units not typically seen in Canada. As they hear about, for example, a 50 centilitre (cL) bottle of juice, discuss whether it would be more or less than 50 mL. They might want to explore this through their own research.
Have students colour-code a metre stick to show decimetres. Ask them to measure different lengths using millimetres, centimetres, decimetres, and metres (in Grade 4, students write with decimals to tenths, so they could express the measure by saying 1 m plus 100 mm, or 1.1 m, or 11 dm). Support students in recognize “times 10” relationships on the metre stick and in making connections to the place-value system.
solve problems involving elapsed time by applying the relationships between different units of time
Support students in using open number lines to keep track of and calculate elapsed time. Have students share their strategies and discuss the different approaches. Have them use timelines to track elapsed-time problems involving both dates and times.
Have students use open number lines to keep track of and calculate elapsed time. For example:
Use bus or train schedules to create elapsed-time problems involving the 24-hour clock (e.g., “How long does it take for the bus to get from point A to point B?”). Have students move between the 24-hour clock and a.m.–p.m. conventions, and structure problems to increase in complexity, such as:
Have students pose and solve elapsed-time problems that involve using schedules based on a 24-hour clock (e.g., bus or train schedules). For example, if a train leaves at 06:30 and arrives at 23:15, how long is the train ride?
Vary the structure of elapsed-time problems (i.e., what is known and unknown), including the following:
identify angles and classify them as right, straight, acute, or obtuse
Have students use their arms to model a right angle, an obtuse angle, an acute angle, and a straight angle. As well, have them turn their bodies to face different directions, showing right, straight, acute, and obtuse angles as amounts of turn. To connect with their learning about the properties of light in science and technology lessons, have them describe the angle of a ray of light reflected off a mirror.
Have students find right angles and perpendicular lines in objects around the classroom or school by using the corner of a sheet of paper as a “right-angle tool” to make comparisons directly. Have them also look for objects with angles that are greater than or smaller than a right angle and classify these as acute or obtuse. Have them add examples of straight angles to the list and discuss how a straight line is also a straight angle. Connect to learning from E1.1 by using the property of right angles to distinguish rectangles from other shapes, such as parallelograms and rhombuses.
use the row and column structure of an array to measure the areas of rectangles and to show that the area of any rectangle can be found by multiplying its side lengths
Provide students with 24 square tiles and ask them to build different rectangles. Have them state the dimensions of each rectangle. Support students in making connections between the dimensions of their rectangles, the row and column structure of an array, and the area of their rectangles (24 square tiles); for example, the base tells the number of columns and the height tells the number of rows. Repeat for other quantities of square tiles.
Provide students with paper squares and outlines of rectangles – some of which require the paper squares to be cut in half to fill the rectangle. Ask them to arrange the paper squares in rows and columns to fill in the rectangle, and tell them that they can cut the paper squares if they need to. Ask them to make connections between the dimensions of their rectangles, the row and column structure of an array, and the areas of their rectangles.
Provide students with rectangles sectioned into rows and columns, with part of each rectangle obscured or erased. Have students predict the area of each rectangle, then ask them to verify their predictions by filling in the missing lines to complete the row and column structure. Support them in using multiplication facts to determine the areas of the rectangles.
apply the formula for the area of a rectangle to find the unknown measurement when given two of the three
A = l × w
A represents area.
l represents length.
w represents width.
A = b × h
b represents base.
h represents height.
Pose problems where students are tasked to find an unknown area, base, or height when two of the three measurements are given. Have students brainstorm real-life and relevant spaces and objects that are rectangular (e.g., the floor area of the community centre), and use these contexts in posing and solving problems. For example:
For each problem, have students identify the multiplication and division sentences they could write and highlight the relationship between multiplication, division, and the measurement of area. Ensure that students recognize that a measurement needs both a number and a unit, and support them in choosing the appropriate unit for area and length.