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Worksheet Grade 5 Science

Weighing What's Left: A Grade 5 Evaporation Test at Briarcliff Pond

A grade 5 worksheet where students weigh pond water before and after evaporation to find the weight of dissolved solids left behind in each sample.

Objectives

  1. Students will subtract measured weights to find the weight of water and of dissolved residue in a sample.
  2. Students will explain why clear water is not always free of dissolved material.

Vocabulary

Evaporation
Evaporation happens when liquid water, often warmed by the sun, turns into an invisible gas called water vapor that rises into the air. It is how water leaves oceans, lakes, and puddles.

Also: dissolved, residue, conserve, sample

Teacher overview

A class studying Briarcliff Pond, a fictional site used for this worksheet, collected three water samples and ran a simple test: they weighed each empty cup, weighed the cup after adding pond water, let the water evaporate over about a week, and then weighed the cup one last time. A common misconception this worksheet addresses is the idea that when water "disappears" through evaporation, everything that was dissolved in it disappears too; the weight data in this worksheet shows that the dissolved material stays behind even after the water itself is gone. The residue weights in this worksheet are larger than most real ponds would give, because 100 grams of typical pond water leaves only a few hundredths of a gram of residue, so a class repeating the test needs a larger sample or a very sensitive scale.

Weighing What's Left: A Grade 5 Evaporation Test at Briarcliff Pond — Grade 5 Science
Name: ____________________________ Date: ______________

Student Worksheet

  1. Sample A's empty cup weighs 20 grams. Cup plus pond water weighs 120 grams. How many grams of water were added?
  2. The water in Sample A evaporates. The cup and leftover residue now weigh 20.6 grams. How many grams of residue are left?
  3. Sample B's empty cup weighs 22 grams. Cup plus water weighs 122 grams. How many grams of water were added?
  4. After evaporation, Sample B's cup and residue weigh 23.4 grams. How many grams of residue are left?
  5. Sample C's empty cup weighs 18 grams. Cup plus water weighs 118 grams. How many grams of water were added? After evaporation, the cup and residue weigh 18.2 grams. How many grams of residue are left?
  6. Rank the three samples from least residue to most residue.
  7. Which sample's water likely had the most dissolved material before it evaporated? Use the data to explain your choice.
  8. Before evaporation, every cup looked clear. Use the residue data to explain why "clear" does not always mean "nothing is dissolved."
  9. Sample B's residue weighs seven times as much as Sample C's. What might that tell you about the ground each pond's water passed through?
  10. A classmate says, "The water disappeared, so all the material in it disappeared too." Use the weight data to explain what is wrong with this idea.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: 100 grams.
    120 g − 20 g = 100 g of water added.
  2. Answer: 0.6 gram.
    20.6 g − 20 g = 0.6 g of residue.
  3. Answer: 100 grams.
    122 g − 22 g = 100 g of water added.
  4. Answer: 1.4 grams.
    23.4 g − 22 g = 1.4 g of residue.
  5. Answer: 100 grams of water; 0.2 gram of residue.
    118 g − 18 g = 100 g of water added. 18.2 g − 18 g = 0.2 g of residue.
  6. Answer: Sample C, then Sample A, then Sample B.
    Residue weights were 0.2 g (C), 0.6 g (A), and 1.4 g (B), so from least to most the order is C, A, B.
  7. Answer: Sample B.
    Sample B left behind the greatest residue weight, 1.4 g, after the same 100 g of pond water was added to each cup, meaning its original water carried the most dissolved material.
  8. Answer: Dissolved material can be invisible in water yet still have weight.
    All three samples looked clear before evaporation, but every sample still left measurable residue behind once the water evaporated, showing that material can be dissolved and invisible while still adding weight to the water.
  9. Answer: Answers will vary but should reason that Sample B's pond water likely passed through soil or rock with more minerals available to dissolve, or spent more time in contact with the ground, than the water collected for Sample C.
  10. Answer: The water changed form rather than disappearing completely.
    The liquid water evaporated and left the cup as water vapor, but the dissolved solid material did not evaporate with it and stayed behind as residue, which is why every cup still weighs more than its original empty weight even after all the liquid water is gone.

Differentiation

Support (below grade level)

Provide a simple subtraction template for items 1 through 5 ("cup + water weight" minus "empty cup weight" equals "water weight"), and allow students to use a calculator for all subtraction steps.

Extension (above grade level)

Ask students to design a fourth sample with a residue weight between Sample A's and Sample B's, stating its cup-plus-water weight and its after-evaporation weight so that the numbers are consistent with a residue in that range.

ELL supports

Pre-teach "dissolved," "residue," and "evaporation" with a simple three-panel picture showing a cup of clear water, the same cup with rising wavy lines representing evaporation, and the empty cup with a small speck left at the bottom. Allow items 6 through 10 to be discussed with a partner before writing.