Pattern | table | graph | rule Lesson overview Outcomes Students work through the process of, and make connections between, creating a geometric pattern; writing a table of values; plotting points on a graph; and forming a rule using the Bridge builder learning object, a SMART notebook file and plotting points in GeoGebra. Stage 4 Software used Learning objects, SMART Notebook, GeoGebra PAS4.1 Uses letters to represent numbers and translates between words and algebraic symbols. PAS4.2 Creates, records, analyses and generalises number patterns using words and algebraic symbols in a variety of ways. PAS4.5 Graphs and interprets linear relationships on the number plane Stage 5 PAS5.1.2 Graphs linear relationships from equations. Stage 6 General Mathematics AM2 Modelling linear relationships Activity 1 Introduction Hanging out the washing Take a piece of rope, some pegs and some tea towels into class. Tie the rope across the classroom and start to hang out the tea towels – using two pegs per tea towel. Pause and ask the students these questions: Take the tea towels off and start rehanging them with one peg per towel, asking: If I was short on pegs one day and could only use one peg per tea towel, how many pegs would I need to hang out 50 tea towels? Are you sure? How did you work it out? How many pegs will I need to hang out 50 tea towels? What about pegs for 100 tea towels, 67 tea towels...? Are you sure? What’s the rule to help me work it out? How did you work it out? How many pegs will I need to hang out 100 tea towels, 34 tea towels... ? What is the rule that will work out the number of pegs I need for any amount of tea towels? Ask students for other suggestions of ways to hang tea towels and discuss the rule needed to work out the number of pegs. A pattern students often suggest is when two towels share a common peg. The same problem from a different perspective If I had a limited amount of pegs: © Commonwealth of Australia 2009 How many tea towels could I hang out using my two pegs per towel system if I only had 30 pegs? 100 pegs? 23 pegs? How did you work it out? What is the rule? What is the rule using the one peg per tea towel system? Using the share a peg system? Page | 1 Teaching notes Activity 2 Demonstration The introductory activity is designed to actively engage students and lead into algebraic thinking of generalising a pattern into a rule. Using learning objects Encourage students initially to give a verbal description of the pattern in words. For example, you need two pegs for every tea towel. Download and use the Bridge builder: triangles 1 learning object by searching on TaLe using the search term Bridge builder. Then suggest students could represent the number of tea towels with a pronumeral ‘T’ and the number of pegs with a pronumeral ‘P’. Ask your students if they think T = 2P is correct. Have them justify their answers. The important concept to develop is the notion of a variable. There is a relationship between T (the number of tea towels) and P (the number of pegs). If the number of tea towels to be hung varies so do the number of pegs required to hang them and vice versa. Encourage students to record the pattern in a vertical table. For example, T P 1 2 2 4 3 6 Using a vertical table enables students to clearly see the ordered pairs of points to be plotted on the number plane later. Challenge task Ask students, in pairs, to describe three different ways of hanging out tea towels. For each scenario they need to: Draw the washing line showing the tea towels and the pegs Describe the pattern in words Record the pattern in a vertical table Write the rule for the pattern © Commonwealth of Australia 2009 Demonstrate this resource to students using a laptop and data projector or an interactive whiteboard. Alternatively, students could access the resource directly from TaLe using their laptops. Work through the resource by following the instructions embedded in the learning object. Ask students for their input along the way by using miniwhiteboards or other methods. Make clear verbal and visual connections between the pattern formed, the way the table is completed and the plotting of the points. More learning objects The TaLe website includes more learning objects that support development of the concept of a variable. Search TaLe using these search terms: Bridge builder: triangles 2 Bridge builder: quadrilaterals Bridge builder: complex squares Bridge builder: complex pentagons Circus towers: triangular towers Circus towers: square stacks Circus towers: square pyramids Circus towers: rectangular prisms Circus towers: triangular prisms Page | 2 Activity 3 Investigation Points can be hidden by clicking the blue dot next to the point in the algebra window. To delete points, right click on the point in either the drawing pad or algebra window and select delete. Using SMART Notebook file Open the SMART Notebook file Patterns. This file may be used for teacher demonstration or as a file students interact with on their laptops. To draw a line in GeoGebra, choose the Line between two points tool Decide how important it is for your students to create a physical model of each pattern. The visual image may assist them to complete the table. Students complete the table; either within the Notebook file on their laptop or in their maths book and then complete the rule in words. Click once on the first point, then once on the second point. The equation of the line will appear in the algebra window. Drag down the pull tab at the top of the screen. Students now open GeoGebra and plot the points in the table (you may need to demonstrate how to do this the first time). Type points into the input bar at the bottom of the window in the same way as you would write them eg (0,6) enter You can choose to show or hide the grid and axis by clicking on View and selecting or deselecting the options shown. Note: If students are filling in answers onto their Notebook file, you may like them to take clips of each page when completed and put into OneNote alongside the graph they create in GeoGebra. Work through pages 2-7 of the Notebook file Patterns either as a class, individually or in pairs. Discuss page 8 as a class. Points are listed in the algebra window (on the left hand side) in the order they were plotted. The blue pages are examples of one step rules. The green pages are examples of two step rules. The green page patterns have joining sections. Challenge the class to come up with other one or two step rule patterns. © Commonwealth of Australia 2009 Page | 3 Play a game of Guess my rule. Allocate pages 9-13 to either individual or pairs of students. Students can: draw up a table of values (in their books, Excel or Word) plot the points in GeoGebra work out the rule. If students find this easy, challenge them to work out the rule without plotting points in GeoGebra i.e. from the points in their table of values or straight from the diagram. Students present their findings to the class. Students work through pages 18-20 individually. Use page 21 and the way GeoGebra describes the line (in equation form) to discuss the use of symbols to represent words e.g. N represents the number of toothpicks. Page 21 Students work through pages 22-24 either individually or in pairs, plotting points to check their work. © Commonwealth of Australia 2009 Page | 4