Units & Systems

Paraphrase:

Have you ever mixed up the names of two people, like classmates at school? Mix-ups seem to happen most often when two people are similar in some ways. The same happens in science. It’s easy to mix up terms that sort of mean the same thing, but not exactly.

Let's look at some examples.

Show mass/weight panel. Paraphrase:

Mass and weight are similar ideas. They both tell about how much matter is in an item. The difference is that mass does not change due to gravity, but weight is measured using gravity (like the apple on the scale). Think about it: You would weigh less on the moon, but your mass would be the same.

Show volume/capacity panel.

Volume and capacity are similar ideas. Volume describes the amount of space that something takes up, whereas capacity describes the space in a container that can contain (hold) a substance.

(Show length/distance panel. Paraphrase:

Length and distance are similar ideas. Length is usually used when referring to the long side of something, and it implies straightness. Distance simply means how far two points are from each other.

Distribute worksheet "Concept Cousins."

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Have students work in pairs to create sentences that are accurate and that make sense given their new understanding of this terminology.

Ask students to assemble sentences about measurements using the word strips they have cut up. Remind them they can use the pictures on the previous page as a reference. Students may need some additional guidance and modeling.

Once partners have agreed on the sentences, have each student write the sentence on the blank lines beneath each image on the previous page.

This activity is similar to the DARTS instructional strategy from Reading to Learn in Science. This "Reconstruction DART" format challenges students to re-assemble segmented and disordered text.

After the students have spent 5 minutes generating their own sentences, spend a few minutes reconstructing sentences as a class. If you are projecting on the whiteboard, you can trace lines to string the sentence parts together.

Answers:

• The mass of the gold bar is 1 kilogram.
• The weight of the apple is about 150 milligrams.
• The volume of the puzzle cube is 27 cubic inches.
• The capacity of the measuring cup is 1 pint.
• The length of the ladder is 12 feet.
• The distance from San Francisco to Philadelphia is 2,441 miles.

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This section shows students how to “upgrade” their language to more precise and formal scientific language. The third example asks that students fill in the blanks.

Paraphrase:

Younger students compare objects by looking at them and saying something like, “The dog is bigger than the cat.” While there is nothing wrong with this, students must be capable of making comparisons that provide more information before they enter high school.

Distribute worksheet Comparing Items Beyond “Bigger” and “Smaller”

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Students may need a mini-lesson on how to write more precise sentences when comparing items for measurement.

Below are two comparisons from the worksheet. Have students write the informal, less precise comparison sentences as well as the more scientifically accurate sentences.

Sample Answers:

• It is longer to El Paso than to Texarkana. / The distance to El Paso from Austin is 200 miles greater than the distance to Texarkana.

• The containers have different amounts / The volume of the liquid on the left is 7 ml less than the one on the right.
• Bonus: Both cylinders have the same capacity.