How much do the cubes weigh in grams?
Plan Investigating Standard Measures 2
Students have been thinking about the cubes and their relative weights for a while. In this investigation, they see those relationships expressed in grams. While the activity is simple — just weigh and compare — students’ thinking about weight becomes more sophisticated.
Formative Assessment
Available online at inquiryproject.terc.edu
Students weigh the cubes in grams and place them on the weight line. As they study the array, they focus on two embedded ideas: the additive nature of weight and the continuous nature of weight. They also have another opportunity to ponder why these same–sized cubes have such different weights.
By the end of the investigation, students will be able to describe more explicitly how the weight of one cube compares to another.
Learning Goals
- to determine the gram weight of the materials cubes
- to use a weight line to compare the weights of objects
- to consider the additive nature of weight
- to appreciate the continuous nature of weights
| Sequence of experiences | ||
|---|---|---|
| 1. Ask the question | All Class | 5 Mins |
| 2. Weigh the cubes in grams | Small Groups | 15 Mins |
| 3. Add the cubes to the weight line | All Class | 5 Mins |
| 4. Make meaning | All Class | 15 Mins |
Materials and Preparation
For the class:- Post the investigation question in a place where all students can see it.
- Make a class table on a whiteboard or flip chart for recording the gram weights of the cubes; an example is shown in Step 2.
- the plastic weight line
- 1 index card labeled “Grams”
- 2 or more sets of materials cubes (each student needs one cube to weigh)
- 2 cubes that have been cut in half
- 1 gram weight set
- 2 pan balances
Notebook Pages
Do students know the weights of the 8 cubes in grams? Do they understand why they'll use grams as the standard unit of weight?
Look at notebook entries to find evidence that the student has an accurate record of the weight of each cube in grams. You'll also find evidence of their understanding of the rationale for using grams to weigh things.
Use these criteria to interpret student work:
- The cubes should weigh approximately:
Pine 7g, Oak 13g, Nylon 18g, Acrylic 19g, PVC 22, Aluminum 44g, Steel 128g and Copper 147g. Humidity will affect the weights of pine and oak, and the (in)accuracy of the balances may cause the measurements of all cubes to vary by one or two grams. - Rationales for using grams:
this is the unit used by scientists around the world, like paper clips, they are light enough to discriminate between objects that are very close in weight.
Next steps might include selecting another small object, estimating its weight in grams, and weighing it.
