```Tennessee Department of Education Task: Tree House Windows 5th Grade Tom and Gina are thinking about the number 2.3 mils, which represents the thickness of the plastic sheeting used to cover windows of their tree house to keep out the wind in the winter. The teacher asks each of them to create a representation of the number 2.3 using place value blocks. Tom chose a flat for his unit and represented 2.3 with two flats and 3 rods. Gina chose a cube for her unit and represented 2.3 with two rods and 3 cubes. a. Which do you think is the better representation for the number 2.3? Explain your reasoning. b. Consider the representation you did not choose for part a. Explain why you don’t think it is the best representation. c. Create and draw your own representation of the number 2.3 using a rod for your unit. Explain why this representation is also appropriate. Teacher Notes: If students do not include place value and the relationship between and among blocks in their explanations, teacher should guide students to include this level of detail. As a means of differentiation, you could change Gina’s representation to 2 flats and 3 cubes because this requires only one level of place‐value explanation, as opposed to the problem as written, which requires two levels of place value explanation. Any block can be chosen to represent the unit as long as there is a block that is smaller than it by 1/10 to represent the 0.3. Common Core State Standards for Mathematical Content Common Core State Standards for Mathematical Practice 1. Make sense of problems and persevere in solving them. 2. Reason abstractly and quantitatively. 3. Construct viable arguments and critique the reasoning of others. 5.NBT.A.1 Recognize that in a multi‐digit number, a digit in one 4. Model with mathematics. place represents 10 times as much as it represents in the place to its 5. Use appropriate tools strategically. right and 1/10 of what it represents in the place to its left. 6. Attend to precision. 7. Look for and make use of structure. 8. Look for and express regularity in repeated reasoning. Essential Understandings •