In this unit we compare the lengths of the students’ favourite soft toys directly and then indirectly using multi-link cubes.
- Compare a group of 3 or more objects by length.
- Measure length with non-standard units.
In this unit the students begin by making direct comparisons between objects and putting a number of objects into order according to length. They are also introduced to measuring with multi-link cubes which allows them to compare objects which cannot be placed together.
Multi-link cubes are an example of a non-standard measuring unit. They reinforce most of the principles that underpin measurement and allow students to find out that:
- You must not change the unit being used when you are measuring an object.
- Units are chosen for their convenience and appropriateness to the object being measured.
- Units are placed end to end in a straight line and then counted to find the distance (length) between two points.
- You express measurements to the nearest whole unit or to a specified degree of accuracy, for example, almost 5 handspans, or about 6 ½ straws long.
The students will also be encouraged to estimate. Initially these estimations may be little more than guesses, but estimating involves the students in developing a sense of the size of the unit. As everyday life involves estimates at least as frequently as exact measures the skill of estimating is important.
- Multi-link cubes (or blocks)
- Rods (the 10 rod is best)
- A teddy bear or soft toy from home
- Large sheets of paper for drawing around the toys
- A roll of paper for drawing outlines of the students
In preparation for this unit have all students bring a favourite soft toy to school.
- We begin the week by looking at all the soft toys the students have brought to school. Ask the students, seated in a circle, to introduce their soft toy to the class.
- Ask a student to put her toy in the centre of the circle.
Do any of you have toys that are taller than this?
- Let the students take turns bringing their toys into the centre to compare.
- Put taller toys in one group, shorter toys in another and toys of the same height in the third group.
- After heights have been compared ask the students to suggest other ways that the toys could be compared. For example: bigger or smaller feet, longer or shorter legs, and bigger or smaller puku.
- Ask groups of 3 students to put their toys into an order. As they do this ask questions that require them to describe the size of the attribute they are using a referent.
- See if the other students can guess the attribute that the groups have used to order their toys.
- Show the students how to trace outlines of their toys on paper which they can colour to make life-sized portraits for use later in the week.
For the next 3 days we make comparisons using the students. They draw outlines of their bodies and then make measurements using mulit-link cubes and rods.
- Demonstrate how to draw around a student to get an outline. Show that they need to draw around both arms and legs.
- Give each of the students a cube and ask them to estimate (guess) how many cubes you would need to measure the length of the arm.
- Check the estimates by measuring with the cubes.
- Now give them a rod and ask them to estimate again. By asking them to explain or justify their guess you can focus their attention on the size of the rod in comparison to the cube.
- Check the estimates by measuring with the rods.
- Ask the students what other parts of the body they would like to measure. List these on a chart (with drawing) for later reference.
- Have the students draw outlines of each other and then measure the length of their legs, feet, fingers using either cubes or rods.
- If the students choose to measure their waist you will need to discuss how they can measure around something. Discuss how they could use string to mark off the distance around their waist and then measure the string with cubes.
- Ask the students to record their measurements on their outline.
- If the students complete measuring their outline ask them to measure the outline of their toy.
- At the end of each day, share work and make comparisons.
Whose arm measured more than 25 cubes?
Tell me how many more.
Which parts of your body measured shorter than your arm?
Which is your smallest measurement?
Which is your largest measurement?
What have you measured with rods? Why did you choose rods?
Have you ever been to a place where you were measured? Tell us about it.
Today we line up the outlines of our soft toys ready to go to school assembly (the shortest in the front.)
- Ask the students to measure the height of their soft toy using linker cubes and record this on the outline. Have them cut off any extra paper from the top and bottom of the outline.
- Tell the students that the toys want to go to the school assembly and so that everyone can see them arriving they will need to stand in order from the short ones to the tall ones.
- Ask four students to come to the front of the room with their outlines. Ask them to put their outlines in order (using the edge of the board). Let the other students check the order.
- Now let the other students, in turn, put their toy outlines in the line. As they place their outline ask them why they have chosen that place.
- Continue discussing, comparing and moving outlines until all the toys have been ordered.
- Display the line in the hallway so that other students and parents can see it.