Understanding place value is crucial if students are to develop the estimation and calculation skills necessary to become numerate adults. Our number system is based on groupings of ten. Ten ones form one ten, ten tens form one hundred, ten hundreds form one thousand, and so on. The system continues, giving us the capacity to represent very large quantities. The Place values such as one, ten, one hundred, one thousand are powers of ten. That means that the place immediately to the left of a given place represents units that are ten times more than the given place, e.g. thousands are ten times greater than hundreds.
Ten digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are used to represent all the numbers in a base ten number system. A new number is not needed to represent ten, because it can be thought of as one group of ten. Similarly, when one is added to 999, we write 1000. Therefore, we do not need a separate number symbol for one thousand. The position of the 1 in 1000 tells us about the value it represents. Zero has two uses in the number system, as the number for ‘none of something’, e.g. 6 + 0 (i.e. none of something) = 6, and as a placeholder, e.g. 7040. A number is a placeholder when it occupies a place, or several places. This allows for communication of the values represented by other digits. For example, in 7040 zero acts as a place holder in the hundreds and tens places. In turn, this communicated the value of the 7 and 4 digits.
Place value means that both the position of a digit, as well as the value of that digit, indicate what quantity it represents. In the number 2753, the position of the 7 is in the hundreds column, meaning it represents seven hundred. 2 is in the thousands column which means that it represents two units of one thousand, called 2000.
Understanding the nested nature of place value is necessary for students to operate on whole numbers and decimals. Nested means that the places are connected, e.g. within hundreds there are tens, within ones there are tenths. Renaming a number flexibly is an important application of nested place value.
In particular, it is vital that students understand that when ten ones are combined they form a unit of ten, when ten tens are combined they form a unit of one hundred, and when ten hundreds are combined they form a unit of one thousand. For example, the answer to 2610 + 4390 is 7 thousands since 610 and 390 combine to form another thousand. Similarly, when a unit of one thousand is ‘decomposed’ into ten hundreds, the number looks different but still represents the same quantity. For example, 4200 can be viewed as 4 thousands, and 2 hundreds, or 3 thousands and 12 hundreds, or 2 thousands and 22 hundreds, etc. Decomposing is used in subtraction problems such as 7200 – 4800 = □ where it is helpful to view 7200 as 6 thousands and 12 hundreds.
At Level 3 students need to develop a multiplicative view of place value that includes understanding the relative size of quantities represented by different numbers. A nested view of 230 as 23 tens allows multiplicative connection between 23 and 230. 230 is ten times larger than 23, and 23 is ten times smaller than 230. Such knowledge can be expressed with equations, 23 x 10 = 230, 10 x 23 = 230, 230 ÷ 10 = 23. Multiplication and division basic facts can be leveraged for harder calculations, 4 x 3 = 12 so 4 x 30 = 120 (ten times more). 30 x 4 = 120 as well. 12 ÷ 3 = 4 so 120 ÷ 30 = 4.
Houses
This unit seeks to connect learning outcomes, and provide problem solving opportunities across all five content strands, number, geometry, statistics, algebra, and measurement. The context of houses is used to develop concepts such as drawing and modelling 3-dimensional objects, using coordinate systems to locate position, find the possibilities of events, and identify paths through simple networks.
This multiple-strand unit covers a wide range of mathematics topics including: properties of triangles and quadrilaterals, networks, nets and diagrams of 3-dimensional solids, coordinates on a number plane, and combinations. Students need to have knowledge of 3D shapes (e.g. cuboids), 2D shapes (e.g. triangles) and of how to read coordinate pairings.
It supports students who are working within stage 6 (advanced additive) of the Number Framework. At stage 6 a student can estimate answers and solve addition and subtraction tasks involving whole numbers by choosing appropriately from a broad range of strategies (for example place value partitioning, rounding and compensating or reversibility). The student uses a combination of known facts and a limited range of strategies to derive answers to multiplication and division problems (for example doubling, rounding or reversibility).
This unit can be differentiated by varying the scaffolding provided to make the learning opportunities accessible to a range of learners. For example, drawing views of 3-dimensional structures can be scaffolded using variables like:
The practical nature of the tasks in the unit requires access to physical and diagrammatic resources. Providing materials, and putting varied demands on what tasks are carried out mentally, is a powerful tool in catering for diversity.
The contexts in this unit can be adapted to reflect the cultural and geographical diversity of your class and environment. For example, historic home tours might be connected to tours of local important buildings (e.g. the buried village outside Rotorua, or the Waimunga Valley pathways, the Dunedin railway station). Constructing nets for solids might be framed around models of wharenui or wharekai, or of significant buildings in the local area.
Te reo Māori vocabulary terms such as inea (to measure), tapawhā (quadrilateral), tapatoru (triangle), taunga tukutuku (coordinates), and tūponotanga (probability, chance) could be introduced in this unit and used throughout other mathematical learning.
Session 1
Session 2
The context of this session involves discussion of the distance different students live from school. If you feel this context is not appropriate for your class, you could reframe the learning in the context of planning a school trip. You could choose three different places for the class to “visit” on this hypothetical class trip (e.g. the museum, the swimming pool, the marae). Finding the middle point of these locations could be presented as finding the best location for a lunch stop. In a historical context, the three places could be chosen from places where the Treaty of Waitangi was signed (e.g. Waitangi, Manukau, Opotiki, Akaroa, Ōnuku, Ruapuke Island).
Ask several students in the class how far they live away from the school. They may give their answers in distance or travel time. Comment that they are going to investigate where the school should be to make it as central as possible. Ask two students to mark as accurately as possible where their house is on a street map of the area. Ask the students if the school is central (in the middle) of these two houses. This is easy to visualise by drawing a line between the two locations:
Discuss the methods that students have used. These might be focused on features of the triangle, particularly equally splitting angles and sides. Such methods might produce solutions like:
Split the angles method.
![Diagram showing the 'splitting the angles' method of finding the central location of a triangle.](/sites/default/files/inline-images/houses-5_0.png)
![Diagram showing the 'splitting the sides' method of finding the central location of a triangle, which does not give a sensible solution.](/sites/default/files/inline-images/houses-6.png)
![Diagram of the 'width by height' method of finding the central location of a triangle.](/sites/default/files/inline-images/houses-7.png)
![Diagram of the 'co-ordinate' method of finding the central location of a triangle.](/sites/default/files/inline-images/houses-4.png)
Split the sides method that, in this case, does not appear to give a sensible solution.
Width by height method. Draw the smallest rectangle that includes all of the corners and cut the sides in half. The intersection of these “bisectors” gives the centre.
The co-ordinate method. Each house location is given an ordered pair and the average of the x-coordinates and the average of the y-coordinates is found. This gives the centroid or balance point of the triangle.
The average of the coordinates gives the point (7, 4.33…). In this case the coordinate averaging method seems to give a good indication of the centre.
Discuss with the students which of these methods will also work if we consider finding the centre of four or more houses. They may conclude that the length by width and coordinate methods will always work, no matter the number of houses. The split the angles and sides methods could be tried with some quadrilaterals to determine if they will work.
Name
X coordinate
Y coordinate
Joe
3.5
6.4
Gill
0.9
8.7
Shirley
6.5
1.2
…
…
=average(B2:B?)
=average(C2:C?)
Session 3
Session 4
Using tables
Using tree diagrams
Roof Walls Door/Windows
Focusing on the structure of these models reveals that the six combinations are found by finding three possibilities for the roof colour multiplied by two possibilities for the walls (that is 3 x 2 x 1).
Similarly drawing the tree diagram will reveal four possibilities for the roof colour multiplied by three possibilities for the wall colour multiplied by two possibilities for the door/windows colour (4 x 3 x 2 = 24).
Roof Walls Door/Windows
5 colours x 4 colours left x 3 colours left gives 60 possibilities.
What happens to the number of possibilities if it is decided that the roof, windows, and doors are painted the same colour?
What happens to the number of possibilities if the windows and door are painted in different colours?
You have these digit cards in a pack: 0, 1, 2, 4. You deal out three cards. 4 then 2 then 0 come up.
What other card combinations might have come up?
How many different combinations are there?
Session 5
Is it possible to tour the whole house without returning to the lounge?
If a tourist starts inside the room they must return to it.
If a tourist starts outside the room they must end up leaving it.
For a room with an odd number of doorways the opposite scenario is true.
If a tourist starts inside the room they can return to it many times but always end up leaving it.
If a tourist starts outside the room they can pass through it several times but will always end up returning to it.
Kia ora parents and whānau,
This week in maths we have been looking at some ideas linked to houses. We've talked about how to draw them, how to find the centre of a group of houses, how to make a strong wall, counting different combinations of colours, and finding paths through room plans.
Ask your child what their favourite activity was and have them explain it to you. You may need a pen and paper!
Place value with whole numbers
This unit builds students’ understanding of place value, extending to 6 digit whole numbers.
Understanding place value is crucial if students are to develop the estimation and calculation skills necessary to become numerate adults. Our number system is based on groupings of ten. Ten ones form one ten, ten tens form one hundred, ten hundreds form one thousand, and so on. The system continues, giving us the capacity to represent very large quantities. The Place values such as one, ten, one hundred, one thousand are powers of ten. That means that the place immediately to the left of a given place represents units that are ten times more than the given place, e.g. thousands are ten times greater than hundreds.
Ten digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are used to represent all the numbers in a base ten number system. A new number is not needed to represent ten, because it can be thought of as one group of ten. Similarly, when one is added to 999, we write 1000. Therefore, we do not need a separate number symbol for one thousand. The position of the 1 in 1000 tells us about the value it represents. Zero has two uses in the number system, as the number for ‘none of something’, e.g. 6 + 0 (i.e. none of something) = 6, and as a placeholder, e.g. 7040. A number is a placeholder when it occupies a place, or several places. This allows for communication of the values represented by other digits. For example, in 7040 zero acts as a place holder in the hundreds and tens places. In turn, this communicated the value of the 7 and 4 digits.
Place value means that both the position of a digit, as well as the value of that digit, indicate what quantity it represents. In the number 2753, the position of the 7 is in the hundreds column, meaning it represents seven hundred. 2 is in the thousands column which means that it represents two units of one thousand, called 2000.
Understanding the nested nature of place value is necessary for students to operate on whole numbers and decimals. Nested means that the places are connected, e.g. within hundreds there are tens, within ones there are tenths. Renaming a number flexibly is an important application of nested place value.
In particular, it is vital that students understand that when ten ones are combined they form a unit of ten, when ten tens are combined they form a unit of one hundred, and when ten hundreds are combined they form a unit of one thousand. For example, the answer to 2610 + 4390 is 7 thousands since 610 and 390 combine to form another thousand. Similarly, when a unit of one thousand is ‘decomposed’ into ten hundreds, the number looks different but still represents the same quantity. For example, 4200 can be viewed as 4 thousands, and 2 hundreds, or 3 thousands and 12 hundreds, or 2 thousands and 22 hundreds, etc. Decomposing is used in subtraction problems such as 7200 – 4800 = □ where it is helpful to view 7200 as 6 thousands and 12 hundreds.
At Level 3 students need to develop a multiplicative view of place value that includes understanding the relative size of quantities represented by different numbers. A nested view of 230 as 23 tens allows multiplicative connection between 23 and 230. 230 is ten times larger than 23, and 23 is ten times smaller than 230. Such knowledge can be expressed with equations, 23 x 10 = 230, 10 x 23 = 230, 230 ÷ 10 = 23. Multiplication and division basic facts can be leveraged for harder calculations, 4 x 3 = 12 so 4 x 30 = 120 (ten times more). 30 x 4 = 120 as well. 12 ÷ 3 = 4 so 120 ÷ 30 = 4.
The learning activities in this unit can be differentiated by varying the scaffolding provided or altering the difficulty of the tasks to make the learning opportunities accessible to a range of learners. Ways to support students include:
This unit is focussed on the place value structure of whole numbers and as such is not set in a real world context. Learning to read and write numbers in Māori or other Pacific languages will support students’ developing understandings, because number names are derived from their place value structure in these languages. Numbers in te reo Māori can be used throughout this unit.
The activities in this unit could be taught in succession over a number of days to provide a concentrated focus on building place value knowledge. Alternatively, selected activities could be used to support place value understanding while students are working on solving number problems.
Activity 1
Have them discuss the zero in the number. Then ask them to remove or ‘zap’ another digit in their number and record the value of the digit they are removing. For example: the 6 in the number 1065 is removed. In doing so 60 is being removed or subtracted from the number. This is clearly shown by using arrow cards.
Ask what they noticed when the 6 (60) was removed. (A zero appeared in its place).
Discuss zero as a placeholder. Zero adds no value to the number, but has the important job of holding a place. Have the students make another of the 4-digit numbers and repeat this.
Activity 2
Have them play Fish for 1000 (Copymaster 2) in pairs or groups of four to consolidate their understanding of the composition of 4-digit numbers.
Students can model the numbers with materials as needed, to support their understanding. They can also relate these to numbers in their own culture.
Activity 3
Point out that when we write the number 1000 there is no space after the 1 and before the three zeros, whilst with 10 000 a space is used to separate the ten from the three zeros. Highlight the fact that 10 thousand is ten times bigger, by highlighting one row (1000) and then counting the rows.
Ask the students to explain why.
Activity 4
Activity 5
Activity 6
Introduce the game 11,111 (Copymaster 4) and support students to play this game in small groups (i.e. 2-4 students).
Dear parents and whānau,
In class we have been learning to understand very big numbers, their value and how to read them correctly. It is important for students to be able to read numbers up to a million and beyond, and understand their structure. It would be helpful if your child could practice this at home. Find examples of real, large numbers (e.g. in real estate or car sales) and practice reading these. Challenge them to find the highest and lowest prices advertised.
Street Maps
In this unit students use street maps as the context to learn about coordinates and grid references, and for giving and following instructions involving directions and distances.
In this unit students are introduced to two ways in which location is represented in real life situations, grid references and coordinates. In both cases the representation is an ordered pair, e.g. F4 as a grid reference, and (6,4) as a pair of coordinates. The convention is to state the horizontal reference (located on the x-axis) first, and the vertical reference (located on the y-axis) second.
In the grid system (left image), a grid reference (F, 4) is used to locate the person in an area. Grid references are frequently used on maps. In the coordinate system (right image) the location of the person is a specific point at the intersection of the lines. The coordinate (6,4) can also be interpreted as a vector from the origin (0, 0). The vector is the combined effect of a shift of 6 units in the horizontal direction, and 4 units in the vertical direction.
The learning opportunities in this unit can be differentiated by providing or removing support to students, by varying the task requirements. Ways to support students include:
Tasks can be varied in many ways including:
The contexts for this unit can be adapted to suit the interests and cultural backgrounds of your students. Using locations that are familiar and of high interest to students will support motivation. The advantage of familiar locations is that students can use their personal knowledge to validate their work. Students often view non-familiar locations through the media. For example, Great Race events are a hobby for some people, and are readily available on television. Students will enjoy a virtual Great Race through an unfamiliar part of Aotearoa. Choose locations that students show interest in, and/or hold particular cultural significance, e.g. world heritage sites that UNESCO has recognised because of the natural or cultural value. This unit offers opportunities for authentic links to be made to procedural writing.
Te reo Māori vocabulary terms such as mahere (map), ahu (direction), and huri (turn) could be introduced in this unit and used throughout other mathematical learning.
Session 1
Where is the school on the map?
Where is the local park/sports ground?
Where is a local shop (dairy, petrol station, bakery, church etc)?
Where is your house?
How would you tell someone else where The Mole and Chicken Restaurant is located? (B3)
Where is the Taupo Hospital? (E2)
What landmark is in the grid G5 (Parts and Service)?
Mobile phone technology has made maps redundant and almost removed the need for navigational tools as well. When have you needed to use a map?
Can you imagine a place where a map might still be useful?
Session 2
What instructions might we give them?
Instructions must include turns (right and left), distances and important things to look for (Street names, buildings, parks, etc.)
Students may know about the scale.
This distance on the strip equals 200 metres in real space. Let’s tell our friend how far they need to walk along (Street name). Align the strip with the street beginning at the place where the friend starts walking. For example, “They will need to walk about 300 metres up Taharepa Road.”
Session 3
What differences can you see between our grid map and this map?
Do students notice that the numbers are located on the lines rather than between those lines?
What is at (6, 2)? (school)
What are the coordinates for the Fountain?...the Fire Station?...Ferris Wheel?
Put ten new landmarks on the map. Label each landmark, e.g. Hospital, MacDonald’s Restaurant, Skate World, Church, Marae. Students should be encouraged to choose landmarks important to them.
Write down a set of ten coordinates for the landmarks in the order you want another team to visit them. Try to make the trip an interesting shape.
Session 4
Students might think of situations where giving a precise location is important, e.g. Flights to a Pacific Island, searching for lost trampers, tracking ships, etc.
Ask: Do you know where these towns are in Aotearoa?
Students might suggest that they are coordinates.
Locate the towns using the coordinates
Use the decimals to get improved precision.
Session 5
In this session students create a map that will be of future use to them. They screen grab the map from Google Maps and impose their own coordinate or grid system on it.
Using their own map students might write instructions using cardinal compass directions (N, NE, E, SE, S, SW, W, NW) and orientation instructions. In pairs the students follow each other’s instructions. The activity can be made more challenging by asking students to include an appropriate scale on the map.
Dear family and whānau,
This week we have been learning about using maps with grid references. The game Battleship is a great way to practice these mapping skills. It would be appreciated if you could take some time to play it with your child:
Discuss with your child places of significance in your family and locate these on a map.
Figure it Out
Equality with multiplication and division
This unit of work investigates how relational thinking is applied to multiplication and division.
The equal sign signifies a balanced relationship between the numbers and operations on either side of the sign.
If the numbers on one side of the equal sign are changed, then relational changes must be made to the other side to maintain equality, e.g. seven is added to both sides.
Understanding the relationship between numbers on either side of the equal sign is fundamental in a range of operational strategies. Importantly, it is integral to the solving of increasingly complex equations in algebra.
Two progressions are implicated in students’ development to think in relational ways with multiplication and division equations.
Variables Progression
Multiplicative Progression
This unit aims at phases 2-4 of the ‘Variables’ progression and 3-5 of the ‘Multiplicative’ progression.
The learning opportunities in this unit can be differentiated by providing or removing support to students, or by varying the task requirements. Ways to support students include:
Ways to extend students include:
The contexts for this unit can be adapted to suit the interests and cultural backgrounds of your students. For example, you could look for arrays in the following ways and use them as contexts for multiplication and division problems:
Te reo Māori vocabulary terms such as whakarea (multiply, multiplication), whakawehe (divide, division), taurite (balance), paheko kōaro (inverse operation), paheko (operation), and ōrite (equal) could be introduced in this unit and used throughout other mathematical learning.
Session 1
This session explores how relational thinking applies to multiplication, with a focus on the commutative and distributive properties. When designing arrays problems consider, and encourage students to think about, contexts in which the arrays might be relevant (e.g. 5 rows of 3 kiwi eggs lined up in an incubation pod). It is also important to consider what multiplication facts will allow students to easily understand the idea of “arrays” and which multiplication facts might act as a cognitive barrier. Group students with different levels of multiplication-facts understanding to encourage tuakana-teina.
Can students explain which array models 3 x 5 and why? (3 x 5 represents either three rows of five or five rows of three so either answer is justifiable)
Some students may recognise that one array is a quarter turn of the other.
Session 2
8 x 5 = 4 x 10
12 x 4 = 6 x 8
14 x 3 = 6 x 6
4 x 15 = 2 x 30
18 x 50 = 8 x 100
6 x 7 = 2 x 21
16 x ? = 8 x 10
12 x 10 = ? x 5
? x 3 = 9 x 6
8 x ? = 4 x 12
24 x 50 = ? x 100
4 x 9 = ? x 3
4 x ♥ = 8 x ♦
♦ x 9 = ♥ x 3
12 x ♥ = ♦ x 6
♥ x 25 = ♦ x 100
Session 3
Give the students the following division problems and have them collaborate (mahi tahi) with a partner to solve them. Allow them to use Copymaster 3 to support them if necessary.
18 ÷ 3 = ?
36 ÷ ? = 9
? ÷ 5 = 8
28 ÷ ? = 4
48 ÷ 6 = ?
28 ÷ ? = 4
35 ÷ ? = 7
? ÷ 3 = 21
Discuss which facts you look for to solve ? ÷ 3 = 21.
Do your students look in the three times tables to look for a product of 21?
Construct arrays where necessary.
Session 4
In this final session students work on the relationship between the distributive property of multiplication and strategies for solving division problems.
What multiplication equation could we write to solve this problem? (? x 3 = 42)
Both equations are asking us, “How many threes are in 42?”
Where is the answer to both equations?
Do your students recognise that 10 + 4 = 14 is the number of fours found in 42?
39 ÷ 3 = ?
108 ÷ 9 = ?
56 ÷ 4 = ?
75 ÷ 5 = ?
84 ÷ 6 = ?
91 ÷ 7 = ?
Encourage students to record their strategies using multiplication or division equations.
Carrots
In this unit we investigate the amount of water contained in a carrot and we use a time series graph to plot the "weight" of the carrot as the water in the carrot evaporates. The students also pose their own carrot investigative questions.
The key idea of statistical investigations at level 3 is telling the class story with supporting evidence. Students are building on the ideas from level two and their understanding of different aspects of the PPDAC (Problem, Plan, Data, Analysis, Conclusion) cycle – see Planning a statistical investigation – level 3 for a full description of all the phases of the PPDAC cycle. Key transitions at this level include posing summary and time-series investigative questions, and collecting and displaying multivariate and time-series data.
Summary or time-series investigative questions will be posed and explored throughout this unit. Summary investigative questions need to be about the group of interest and have an aggregate focus. For example, How many seeds are in a carrot packet? What do carrots weigh? These questions also need to define the variable and the time period for the investigation. For example, How does the weight of the carrot change over the course of the week? (variable – weight of the carrot; time period – one week).
Time series graphs
Time series graphs are used to display numerical data over time. The numerical variable of interest is on the vertical axis. Time is represented on the horizontal axis. For example, the graph below shows the distance travelled each day by an elephant seal (the numerical value) from May 2005 to January 2006 (the time).
The learning opportunities in this unit can be differentiated by providing or removing support to students and by varying the task requirements. Ways to support students include:
The context for this unit can be adapted to suit the interests, experiences and cultures of your students. You could look at the weight of an animal over time, or record growth of a seedling. Alternatively, you could make links to the development of a local school or community garden, links to science-based learning (i.e. around the growth of different plants), or links to crops of fruits and vegetables that were traditionally, or are currently, grown in your local area. The statistical enquiry process can be applied to many topics and selecting ones that are of interest to your students should always be a priority.
Te reo Māori vocabulary terms such as tauanga (statistics), raraunga (data), tātari (analyse) and huritao (reflection, reflect upon) could be introduced in this unit and used throughout other mathematical learning.
Getting Started
Again get the students to share their ideas.
What information will they collect, and how will they record it? Suggest using a table on a device or paper, for example:
Weight of carrot at start: _____________ Weight of container: _________
Final weight of carrot once dehydrated: __________
Exploring
Over the next three days the students in small groups plan and conduct their own carrot investigation.
Reflecting
On the final day we look at and interpret the findings of our first investigation – How much of a carrot is water. We also share our small group investigations with the class.
How much of a carrot is water?
Small group investigations
Dear parents and whānau,
Do you know how much water there is in a carrot?
This week we have been exploring the answer to this and a number of other carrot problems. Ask your child to share their findings to this question plus the other carrot problem they explored.
Figure it out links
A link from the Figure It Out series which you may find useful is:
Fridge Pickers
In this unit, using our fridge as the context, we collect and present data using dot plots and bar graphs. We start to learn about using the computer to display our data and explore features of data display.
Planning an investigation at Level 3 of the New Zealand Curriculum is more complex than at Level 2. At Level 3, students refine their understanding of statistics by conducting investigations that make use of the statistical enquiry (PPDAC) cycle. PPDAC stands for problem, plan, data, analysis, and conclusion. Within this, students begin to talk about situations they have experienced, pose investigative questions, produce plans for a statistical investigation, and may utilise digital graphing and survey tools (i.e. on the computer) in their work.
In this unit the students are introduced to dot plots and bar graphs. The way in which they will need to collect and organise their data is dependent on the nature of their investigative questions. They should start to see, and be able to talk about, distinctive features of their displays such as the groupings and modes. The unit of work Planning a statistical investigation (level 3) provides a full description of all phases of the statistical enquiry cycle.
Dot plots
Dot plots are used to display the distribution of a numerical variable in which each dot represents a value of the variable. If a value occurs more than once, the dots are placed one above the other so that the height of the column of dots represents the frequency for that value. Sometimes the dot plot is drawn using crosses instead of dots. Dot plots can be used for categorical data as well.
Bar graphs
In a bar graph, equal-width rectangles (bars) represent each category or value for the variable. Usually, gaps are included between the bars to demonstrate the distinct, discrete nature of the categorical data (i.e. that each bar represents a different category or whole number). The height of these bars tells how many of that object there are. The bars can be vertical, as shown in the example, or horizontal.
The example above shows the types of shoes worn in the class on a particular day. There are three types of shoes: jandals, sneakers, and boots. The height of the corresponding bars shows that there are six lots of jandals, 15 lots of sneakers and three lots of boots. It should be noted that the numbers label the points on the vertical axis, not the spaces between them.
The learning opportunities in this unit can be differentiated by providing or removing support to students and by varying the task requirements. Ways to support students include:
This unit uses food and students’ fridges as a context for investigations. When implementing this unit, be aware of your students’ socio-economic backgrounds. Access to food may be a sensitive topic for some students. Therefore, this context can, and should, be adapted to suit the interests and experiences of your students. The statistical enquiry process can be applied to many topics and selecting ones that are of interest to your students should always be a priority.
Te reo Māori vocabulary terms such as tūhura (investigate), rapanga (problem) and kohikohi raraunga (data collection) could be introduced in this unit and used throughout other mathematical learning.
Session 1
We begin the week collecting fridge data about our class. We use this information to start to explore new types of data displays.
What do you think a fridge picker is?
Collect ideas from the class and record them on a hard-copy or digital chart.
What statements can you make about us as fridge pickers? (analysis)
Does the display show us anything different?
Preparation for data collection for a home-based activity
How many people in your family do you think are fridge pickers?
What time of the day do you think people fridge pick?
How could we find out?
We think that:
Our fridges will be opened the most before teatime.
That no one will open the fridge between midnight and 6 am.
Sessions 2-4
Over the next three days the students gather information around the theme of fridges or food. They will collect and record the data in a spreadsheet or data table in a software package that allows them to draw statistical displays. In this unit we use CODAP, but other software tools can also be used. Look for tools that allow students to access the raw data (i.e. one row containing the responses for each person or object they collect data on) rather than needing summarised data. Using the statistical graphing tool students will display the information using dot plots and bar graphs, and make statements about what the data shows. If you do not have access to computers then provide students with blank templates to make their dot plots (Copymaster 2) or bar graphs (Copymaster 3).
PROBLEM: Generating ideas for statistical investigation and developing investigative questions
Prompts to help with posing investigative questions include:
PLAN: Planning to collect data to answer our investigative questions
For example: Make of fridge question – using the internet they found 15 different makes of fridges so they picked six that they knew and added an “other” category.
Categories: Fisher and Paykel, Haier, LG, Samsung, Simpson, Westinghouse, Other Type of fridge question – using the internet they found the following categories for refrigerators: All refrigerator, Top (freezer) mount refrigerator, Bottom (freezer) mount refrigerator, single-door refrigerator with freezer capacity, Side by side refrigerator, French door model refrigerator, other.
Finally, the students need to prepare instructions to indicate how others are to respond to their survey questions. At this stage they should also think about how to collect the data, for example using a table to record responses or a digital survey tool (e.g. Padlet, Google forms).
Q1. What is the make of your fridge? If you have more than one, pick the one that is your main fridge. Choose from:
Q2. What type of fridge do you have? If you have more than one, pick the one that is your main fridge. Choose from:
Read the directions.
Are they clear to you?
Can you tell what you are supposed to do?
What do you think they need to change to make the directions clearer?
DATA: Collecting and organising data
Tell the pairs to leave their instructions and tables to record the responses at their desks. This could be in paper format or electronic. Electronic versions could be set up directly in a spreadsheet (e.g. Google Sheets, MIcrosfot Excel) or on a digital document containing a table (e.g. Microsoft Word, Google Docs). Give students time to complete each others' surveys.
Q1. What is the make of your fridge? If you have more than one, pick the one that is your main fridge. Choose from:
Q2. What type of fridge do you have? If you have more than one, pick the one that is your main fridge. Choose from:
ANALYSIS: Making and describing displays
An introduction to using CODAP as a tool for statistical investigations is explained in full in Planning a statistical investigation – level 3 (session 5).
As mentioned earlier if you do not have access to computers then provide students with blank templates to make their dot plots (Copymaster 2) or bar graphs (Copymaster 3).
Possible examples of the types of information students can get on CODAP is below. In these examples the investigative question What are the types of fridges we have? is explored by graphing the two variables separately and then combined.
These first two graphs show the make and then the type of fridge. Because we are using technology, we can also quickly explore the combination of the two variables.
Once students have generated their graphs, they can start to describe the displays.
To describe the display, encourage students to write “I notice…” statements about their displays. If students are not sure what to notice the teacher can prompt further statements by asking questions such as:
Check the “I notice…” statements for the variable and reference to the group. For example: “I notice that the most common make of fridge for our class in Fisher and Paykel.” This statement includes the variable (make of fridge) and the group (our class). Support students to write statements that include the variable and the group.
CONCLUSION: Answering the investigative question
Tell some of the things you learned from the investigations. What are the preferences of students in our class?
What was the most popular choice in your survey?
How can you tell?
How many students made that choice?
Which display is most effective?
Did you have any unexpected results?
Do these displays look alike?
Did the two surveys have the same choices for you to make?
What differences are there between the investigations?
Session 5
In today’s session we use the data we have gathered at home to examine our initial predictions about fridge pickers.
What can you say about your chart?
Which times of the day are the busiest for fridge pickers? Why?
Which times of the day are the quietest? Why?
Who opens the fridge the most often in your home?
Dear parents and whānau,
This week at school we are carrying out investigations and making displays of data using dot plots and bar graphs.
For one day at home this week we would like your family to keep track of how often your fridge gets opened. To do this, ask people to put their initials above the nearest hour each time that they open the fridge. We will be looking at these dot plots at school on ___________.
Provide Copymaster 1.
Figure it Out Links
A link from the Figure It Out series which you may find useful is: