### Estimate Weight in Metric

Estimate, calculate, and compare the metric and U.S. customary weights of favorite everyday objects. Write and erase your predictions on a predict-and-compare table.

1. How do you describe how heavy something is? With your class, brainstorm different words that describe the weight (mass) of objects. Review the common U.S. customary and metric units for measuring weight.

- U.S. customary weight units include the pound and ounce
- 1 pound (lb) = 16 ounces (oz)
- Metric weight units are based on the gram (g)
- 1 gram (g) = 1000 milligrams (mg)
- 1000 grams (g) = 1 kilogram (kg)

2. Explore how heavy each unit feels by holding weights or objects clearly labeled with their weights. Compare metric and U.S. customary weight units by holding them and feeling their heaviness. How does a pound compare to a gram? How does a kilogram compare to an ounce?

3. One way to explore the different units of measurement is to create a predict-and-compare table with a small group. Start with five or six everyday objects such as a crayon, lunch box, math book, snack bar, box of markers, and tissue box. Draw a picture of one of your objects using Crayola Erasable Colored Pencils on construction paper.

4. Weigh the item on a scale or balance (using weights) so you can find its metric weight. Beside its picture, write the metric weight. Next estimate what the weight will be in U.S. customary units. Would you measure it using pounds or ounces? Write your prediction.

5. Now weigh the object to find out the actual U.S. customary weight. Was your prediction close? How does it compare to the number of metric units? Erase your estimate and replace it with the actual U.S. customary weight. Repeat steps 5 and 6 with two or three more objects.

6. Now repeat steps 5 and 6 with the rest of the objects, but this time measure the U.S. customary weight first, and estimate what the metric weight measurement might be.

**Adult supervision** is required for any arts & crafts project. Observe children closely and intervene as necessary to prevent potential safety problems and ensure appropriate use of arts and crafts materials. Some craft items, particularly beads and buttons, are potential choking hazards for young children. Avoid use of such small parts with children younger than 3 years. Craft items such as scissors, push pins and chenille sticks may have sharp points or edges. Avoid use of materials with sharp points by children younger than 4 years. Read all manufacturers' safety warnings before using arts and craft supplies.

- Keep exploring! Now compare metric weight (mass) and metric volume! Start by weighing one milliliter of water. Next predict the (weight) mass of 1 liter of water. Measure on a scale or balance. Make another data table. Experiment with different measurements.
- Get to know your measurement units! Find objects that weigh exactly 1 gram, 1 kilogram, 1 ounce, and 1 pound. Memorize which object corresponds to which unit. Use your new information to estimate the weights of other objects. For example, if two paper clips weigh about 1 gram, what would a paper towel weigh in comparison?
- Create a conversion chart detailing approximately how many of one unit is equal to how many of another.
- Assessment: Observe small groups working together. Review posters for accuracy and readability.