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Ripples, Striders and a Microscope Quiz

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Ripples, Striders and a Microscope Quiz

Trace sense signals from stimulus to brain to behavior or memory during a pond study week.

The ripple test

Read the passage and Table 1. Then answer questions 1–6.

Pond Week at Fernbrook Nature Center

1Each fall, Ms. Ilse Varga's sixth graders spend a week studying Willow Pond at the Fernbrook Nature Center. The center's educator, Kofi Mensah, helps them collect pond water and small animals, and every animal goes back into the pond at the end of the day. The pond, the people and the numbers here are made up, but they are based on real studies.

2Water striders are insects that stand on the surface of the pond on long, thin legs. When a small insect falls onto the water and struggles, it sends tiny ripples across the surface. Striders have sense receptors in their legs that detect movements of the water's surface. The class noticed that striders often skate quickly toward insects that land on the pond.

3Mr. Mensah put 10 striders in a shallow white tray of pond water, 60 cm long. Student Noor Castellano touched the water at one end of the tray with the tip of a fine paintbrush in four different ways. She ran 3 trials of each way, with a 5-minute rest between trials, and the class counted how many striders skated toward the brush within 5 seconds. In Condition D, a cardboard card stood between the striders and the brush. The card was held 1 cm above the water, so it blocked the striders' view of the brush but not the ripples.

4The class also studied drops of pond water under microscopes. Light from each tiny organism passes through the lenses into a student's eye, where light-sensing cells send signals along nerves to the brain. On Day 1, students used a picture key: rotifers have a crown of hairs that seems to spin, water fleas swim in short jerks, and some algae form long green strands. At the end of each day, Ms. Varga gave a quiz. She showed 10 Willow Pond organisms on a video microscope, and students named them without the key. On Day 4, she also showed 10 organisms from a salt marsh that the class had never studied.

5One morning, Ms. Varga turned the microscope lamps up to full brightness all at once. Several students blinked, and Eli saw the black center of his partner's eye shrink.

Table 1. Skating Toward the Brush (10 striders × 3 trials = 30 tries)
ConditionHow the brush movedTries with skating
AQuick taps on the water27
BOne touch, then held still6
CWaved 2 cm above the water3
DQuick taps, behind a card25
1.

In Condition A, what percent of the tries ended with a strider skating toward the brush? %

2.

Condition A had how many times as many tries with skating as Condition B? Do not round. times

3.
Compare Conditions A and C. What do they show?
Question 3 options
4.
In Condition D, which part of the path from stimulus to behavior did the card block?
Question 4 options
5.
Use Table 1. Which conclusion do Conditions A and D together support best?
Question 5 options
6.
Two flies land on the pond near a group of striders. One is dead and lies still. The other is alive and beats its wings against the water. Based on Table 1, which prediction fits best?
Question 6 options

The microscope quizzes

Use paragraphs 4 and 5 and Table 2 to answer questions 7–12.

Table 2. Microscope Quiz Results (class averages, 10 organisms per quiz)
QuizNamed correctlyTime to finish (min)
Day 1, Willow Pond518
Day 2, Willow Pond713
Day 3, Willow Pond810
Day 4, Willow Pond97
Day 4, salt marsh417
7.

By how many minutes did the average time to finish the Willow Pond quiz drop from Day 1 to Day 4? min

8.
What best explains the change in the Willow Pond quiz results from Day 1 to Day 4?
Question 8 options
9.
Which result is the best evidence that the students improved because of memories of the Willow Pond organisms, and not because their eyes simply got better at seeing through a microscope?
Question 9 options
10.
Circle each event from pond week in which the brain mostly used a memory stored from earlier experience.

11.
On Day 4, Noor sees a rotifer on the screen and writes its name. Which order shows the path of the signals?
Question 11 options
12.
A classmate says, "The striders found the brush by seeing it, the same way we find organisms under the microscope." Do you agree? Write a claim, give evidence from Table 1, and explain your reasoning. Name the stimulus and the sense receptors that most likely led to the striders' behavior.