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Lab / experiment Grade 2 Science

Ivyford Pond's Cloudy Jar: Testing Two Strainers

Grade 2 groups describe a cloth and a screen by their properties, then pour cloudy pond-style water through each and compare which strainer catches more bits.

Objectives

  1. Students will describe a cloth and a screen by hole size, texture, and thickness.
  2. Students will pour the same cloudy water through two strainers and record what each one caught.
  3. Students will name which strainer worked better and give one piece of evidence.

Vocabulary

Key words: strainer, screen, property, clear, cloudy

Teacher overview

The jar in this lab stands in for a scoop from the fictional Ivyford Pond, and the teacher makes it in front of the class from tap water, a spoonful of potting soil, and torn dry leaves, so no student handles real pond water. Groups first describe two materials, a cotton cloth and a plastic screen, by properties they can see and feel, then pour the same cloudy water through each and compare what came out. Expect a prediction that whichever strainer lets water through fastest must also be the one cleaning it best. The screen is the faster of the two and the less effective, so the test puts that prediction directly in front of the class. The brown tint stays in both cups, which sets up the point that a strainer catches only the bits too big to fit through its holes while the finest particles pass straight through.

Ivyford Pond's Cloudy Jar: Testing Two Strainers — Grade 2 Science
Name: ____________________________ Date: ______________

Procedure

Step 1. Your teacher will make the cloudy water. Watch as the soil and leaf bits go in. Do not drink any of the water.

Step 2. Look at your cloth square. Look at your screen square. Feel each one. Write what you see and feel in the first table.

Step 3. Put the cloth over the top of an empty cup. Push it down a little in the middle. Hold it on with a rubber band. This is Strainer A.

Step 4. Put the screen over the top of a second empty cup. Hold it on with a rubber band. This is Strainer B.

Step 5. Fill a third cup half full with the cloudy water. Fill a fourth cup half full too. The two cups should look the same.

Step 6. Pour one cup of cloudy water onto Strainer A. Start the timer as you pour. Stop it when the dripping stops. Write the seconds in the second table.

Step 7. Pour the other cup of cloudy water onto Strainer B. Time it the same way. Write the seconds in the second table.

Step 8. Look at the water in each cup. Look at the top of each strainer. Write what you see in the second table.

Step 9. Wash your hands when you finish.

Data & Analysis

Table 1. What the two materials are like.

Material Hole size: big or small How it feels Thick or thin
Cloth
Screen

Table 2. What happened in the test.

Strainer Seconds to drip through Water color: clear, a little cloudy, or cloudy Bits left on top: many, some, or none
A, cloth
B, screen
  1. Look at the cloth and the screen. Which one has bigger holes?
  2. Rub the cloth with one finger. Write two words that tell how it feels.
  3. Which strainer let the water drip through faster, A or B?
  4. How many more seconds did the slower strainer take? Show your subtraction.
  5. Look at both cups. Which water looks clearer, A or B?
  6. Look on top of both strainers. Which one caught more leaf bits?
  7. The water in both cups is still a little brown. Name one thing your strainer could not take out.
  8. Which strainer would you pick for a big jar of pond water? Tell why.

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: The screen. Its holes are wide enough to see through, while the cloth holes are too small to see.
  2. Answer: Accept any two words that describe touch, such as soft, fuzzy, thick, smooth, or bumpy.
  3. Answer: Accept the answer that matches the group's own recorded seconds. Most groups find that Strainer B, the screen, drips through faster because its holes are larger.
  4. Answer: Accept any subtraction that correctly uses the group's own two recorded times, with the smaller time taken from the larger one.
  5. Answer: Accept the answer that matches the group's own record. Most groups find that the cup under Strainer A, the cloth, holds the clearer water.
  6. Answer: Accept the answer that matches the group's own record. Most groups find more leaf bits left on top of Strainer A, since the cloth stops smaller pieces than the screen does.
  7. Answer: Accept any answer naming the fine dirt or the brown color that stayed in the water. The tiny bits of soil are too small for either strainer to catch.
  8. Answer: Accept either choice when it is backed by the group's own data. A choice of the cloth should cite clearer water or more bits caught, and a choice of the screen should cite the faster drip time.

Differentiation

Support

Build one pair of strainers as a class demonstration before groups build their own, and give these groups a data table with word choices to circle rather than blank cells. Pour for the group while a student runs the timer.

Extension

Have groups fold the cloth in half and run the test a third time, then compare the new drip time and clearness with the single layer result. Ask them to say whether a thicker strainer is always the better choice.

ELL supports

Set out a labeled sample of cloth and screen at each table so the two names stay attached to the objects. Provide the word bank clear, cloudy, fast, slow, many, some, and none for the data tables, and allow answers to questions 1, 3, 5, and 6 to be given by pointing at the chosen cup.