Regents Variables Bell Work Handout
NY Regents Prep Experimental Design Series
Variables & Controls Bell Work
Name:
Date:
Pd:
Complete each warm-up question set. Apply standard NY Regents scientific inquiry criteria.
PROGRESS CHECK: 1 2 3 4
PART 1
Independent vs. Dependent Variables
Regents Standard LE 1.1
Experimental Scenario:
A student investigated how salt concentration affects radish seed germination. Five dishes of 30 seeds each were treated with 0%, 1%, 2%, 3%, and 4% NaCl solutions. All dishes were kept in identical incubators at 22°C. After 7 days, the number of sprouted seeds in each dish was recorded.
1. State the independent variable in this experiment, and explain why it is classified as independent.
2. Identify the dependent variable, and state the exact quantitative data the student collected.
3. Write a formal hypothesis for this investigation using an "If... then... because..." format.
PART 2
Control Group vs. Controlled Variables
Regents Standard LE 1.2
Experimental Scenario:
An investigator tested tea tree oil against E. coli bacteria. Four agar petri dishes were inoculated with identical bacterial lawns. Dish A received a paper disc soaked in sterile distilled water. Dishes B, C, and D received discs soaked in 5%, 10%, and 20% tea tree oil. All four dishes were incubated at 37°C for 48 hours.
1. Identify which dish represents the control group, and state why a control group is necessary.
2. State two environmental variables that must be kept constant (controlled variables) to ensure validity.
Factor 1:
Factor 2:
3. A student changed both the oil concentration AND the incubation temperature for Dish D. Explain why this error invalidates the experimental conclusions.
New York State Regents Science Practice • Part B-2 Core Inquiry Skills Page 1 of 2
NY Regents Prep
Graphing & Data Analysis Bell Work
Student Name: ______________________ Period: ____
PART 3
Constructing a Regents Line Graph
Data Table & Coordinate Grid
A student investigated photosynthesis in waterweed (Elodea). As light distance changed, oxygen bubbles produced per minute were counted.
Experimental Data Table
| Distance from Light (cm) | Oxygen Bubbles (per min) |
|---|
| 10 | 42 |
| 20 | 30 |
| 30 | 19 |
| 40 | 10 |
| 50 | 3 |
Regents Graphing Checklist:
- ☐ Mark an appropriate numerical scale on each axis (no breaks)
- ☐ Label both axes and include proper units
- ☐ Plot all 5 data points accurately and connect with a line
X-Axis Variable:
Y-Axis Variable:
Graph Grid (Plot Data Points & Connect)
Dependent Variable (Y-axis) 0 Independent Variable (X-axis)
PART 4
Graph Interpretation & Predictions
Regents Standard LE 1.3
1. Describe the mathematical and biological relationship shown between the distance from the light source and the rate of photosynthesis.
2. Based on your plotted graph, estimate the bubble count at a distance of 25 cm:
Predicted count: bubbles / min
3. Predict the bubble count if the light source is placed at 70 cm. Justify:
4. Regents Synthesis: State the biological process producing the bubbles, and explain why holding water temperature constant is essential when testing light distance.
New York State Regents Science Practice • Part B-2 Core Inquiry Skills Page 2 of 2
