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4 by 3 rectangle inquiry

Inquiries can begin with the simplest of prompts. Mark Greenaway (an Advanced Skills Teacher in the UK) contacted inquiry maths about developing prompts for level 3/4 students. He proposed using a 4 by 3 rectangle as a prompt. This could potentially lead to a very open inquiry encompassing a number of different directions. However, a prompt like the 4 by 3 rectangle is so familiar to students that it might fail to meet the first criterion for creating a prompt: "A prompt must promote curiosity and questioning in students of the sort 'that can't be right' or 'I've noticed ...'. Prompts should be engaging, and ripe for speculation or conjecture."

There is no guarantee that, beyond stating the obvious features of the rectangle, students will be able to isolate a key concept on which to build an inquiry. For example, a student might be able to identify the area as 12 square units, but not be able to extrapolate from that knowledge the concept of area as a foundation for inquiry. Such a step requires the use of well-developed inquiry skills, and particularly high levels of confidence and creativity.

If students lack those skills, then the teacher will need to define the inquiry further. Teacher intervention at this point reduces the possibility of students working on their own questions and statements, which is a key motivational aspect of inquiry. It is better for the prompt to 'suggest' the key concept so that students can generalise to other cases for themselves. When the rectangle is placed in the context of a series of rectangles sharing the same characteristic (for example, the area), then an initial inquiry can develop out of students' observations.

After the first phase, the teacher can highlight the constraint in the prompt, and invite students to change the prompt by holding another characteristic (for example, the perimeter) of the 4 by 3 rectangle constant. While suggesting changes to the prompt is empowering for students, it remains a highly developed skill. Not only do students have to learn how to be creative, they also have to learn how to make mathematically-valid suggestions.

With these considerations in mind, a more suitable inquiry prompt might show the 4 by 3 rectangle alongside other rectangles of the same area. This might lead to the class posing or answering some of the following questions in its first response to the prompt:
• What is different and the same about the rectangles?
• How many rectangles are possible with the same area?
• Which has the longest perimeter? ... the shortest?
• Is there a rectangle with an area equal to the length of its perimeter?
A discussion can ensue at this point about whether a 4 by 3 rectangle is the 'same' as one with dimensions of 3 by 4. Accepting that they are not, we might speculate that the number of rectangles with the same area is half the area (assuming the dimensions are whole numbers). So there are six rectangles with an area of 12 square units and four with an area of eight. However, if the area is a prime number, there will only be two. The inquiry might develop into a consideration of the factors of prime and composite numbers.

Perhaps,
the teacher prefers to hold the length of the perimeter constant for the initial prompt, when similar questions might arise: • What is different and the same about the rectangles?
• How many rectangles are possible with the same perimeter?
• Which has the greatest area? ... the smallest?
The conjectures that develop from the particular cases shown in the two prompts above might be combined. So, considering the 4 by 3 rectangle, there are six rectangles with an area of 12 square units and six with a perimeter of 14 units. Is this always the case with every rectangle? This path to the inquiry has the potential to reinforce the distinction between the concept of area and that of perimeter.

You can follow Mark Greenaway on twitter @suffolkmaths.

Resources
Prompt sheet

Open inquiry
The teacher can run a fully open inquiry by starting with the 4 by 3 rectangle only. The risk is that, with pressures to 'cover' a curriculum, the inquiry could go in one of many different directions. Alternatively, the teacher could guide the inquiry into those directions by offering prompts in which the 4 by 3 rectangle is an integral part. Indeed, a teacher who starts a series of inquiries with one key component thereby emphasises the inter-connected nature of mathematics.
Prompt 1 - sequences This prompt invites students to pose questions and make comments on sequences: How many sequences are there that contain the 4 by 3 rectangle? Is there another rectangle in this sequence before the three in the prompt? What are the term-to-term or position-to-term rules for the sequences? Can you find an expression (in words or algebra) to describe the area and perimeter for shape n?
Prompt 2 - reflection symmetry
A second alternative prompt invites students to remove squares to create rectangle patterns with lines of symmetry. How many patterns can be created with one line or two lines of symmetry? What if you remove more than two squares? Why can you not make patterns with more than two lines of symmetry? What shape would you need if that was your aim?

For more on the differences between different types of inquiry and on the factors involved in deciding whether to choose an open or guided inquiry, see Levels of Inquiry Maths.
Questioning, wondering and speculating
The picture below shows the questions from a year 7 class. The questions initially focus on the area and perimeter of the rectangles in the prompt before students start to wonder whether it is possible to create other shapes with the same area. One student speculates about the number of rectangles with an area twice the size of those in the prompt. The other two pictures show individual students' contributions to the inquiry.  The pictures were posted on twitter by the students' teacher Aine Carroll‏ (@MissCarrollMath).

Question-driven inquiry
Grade 6 pupils at the Luanda International School (Angola) began their inquiry into measurement by considering the rectangles prompt. As they attempted to make sense of the prompt, the pupils' questions connected their existing knowledge of relevant mathematical concepts to the prompt. The class went on to conduct personal inquiries, during which the generation of even more questions opened up new pathways for exploration. The quality and depth of this generative questioning attests to the sophistication of inquiry processes developed in the class.

You can see other inquiries carried out by the grade 6 pupils on twitter @LIS6point3.

Building resilience and developing creativity
Michelle Cole gave the prompt to her year 7 (grade 6) class as an introduction to the concepts of perimeter and area. She reports that the students’ responses were “inspiring, amazing, and truly beyond any of my expectations.”
The students posed questions on a wide range of mathematical topics: perimeter and area; symmetry, angles, and other properties of the shapes; coordinates; volume; and enlargement by a scale factor of ½. Other questions could have led to novel inquiry pathways:
• How many rectangles (or squares) can you see in each shape?
• How many triangles from one point can you find?
• What shapes can be made out of each shape?
• What fraction of the grid do the shapes take up?
Michelle describes how she approached the inquiry:
I have been experimenting with prompts which in the past I have given a little more structure to but this was the first time I simply gave them the diagram on A3 paper and said “what questions could we ask?”. Students were a little reluctant to put things on paper but once they realised that they had free range to think about questions that we would then discuss they came up with some many and varied ideas. When we discussed their ideas we also talked about which questions we could answer (for example, What is the perimeter? What is the area?) compared to the questions we could not answer (for example, ' Where is the origin? Is there a reason why they are different colours?). We then centred the activity back on perimeter and area with the students investigating the perimeter when they put more than one of their desks together.

I use the ‘what is the same? what is different?’ prompt fairly regularly as a starter (you can see some students have used this as questions on their sheets). It is this that has helped build up their resilience and has got them thinking in a wider context than the most obvious.