**Objective:** Students should be able to use any measuring tool and record measurements to the correct degree of accuracy.

**Prior Knowledge:** The ability to measure with a ruler, graduated cylinder, and a balance beam.

**Time Required:** One 50 minute class period.

**Materials:**Available Measuring tools: - rulers (labeled in centimeters, millimeters)
- graduated cylinders
- triple beam balances, etc.

Items to measure: - string for length
- liquids for volume
- small weighted objects for mass, etc.

**Group Size:** 2 or 3

**Procedures:**- Each group will be given a measuring tool and a couple of items (appropriate for the given tool) to measure, along with a data table*(see below) to record their measurements.
- Students will measure the items and record the length, mass, or volume as they feel is accurate (with no direction from the teacher).
- Students will then rotate to another measuring tool and repeat steps 1 and 2. Continue until students have completed at least one of each type of measurement.
- Students and teacher will assimilate their recordings and discuss any discrepancies or correct/incorrect answers and expected accuracy. Class will then come to a consensus regarding the acceptable accuracy.
**To record accurate measurements, find the smallest division on the instrument, divide by two, and record all measurements to that decimal place.** - Students will then repeat their measurements on each tool and record accurately the length, mass, or volume of each object (see data table).

**Extension:**The students can calculate density by finding the ratio of the mass (m) and volume (v) of an item: Have the students calculate the mass and volume of one (or more) of the liquids they used and determine the density. The teacher may need to get involved in the accurate measure of the mass of the liquid (less the graduated cylinder). Be sure to discuss the number of significant digits in the answer.

**Data Table:**Object or Station | Initial measurement with Units | Revised measurement with Units |

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**Alternate Activity (or assessment) not requiring measuring tools****Materials:**- Handouts or overhead acetates with various diagrams of above-mentioned tools measuring items.

**Group Size:** individual, or in pairs.

**Procedure:**- Have students record measurement for each pictured item.
- Repeat steps 4 and 5 from above procedures.