SEEDS LAB INSTRUCTIONS - GENERAL

Designing an experiment - Day 1 Record notes in the handout! Define terms like “manipulated variable” in your own words. PARAPHRASE my notes (don’t copy them!)

Designing an experiment - Day 1 Manipulated variable The ONE variable that you change in an experiment (what you’re testing) Conditions of the MV Three different levels Example: if temperature is the MV, three conditions could be 40ºF, 50º, 60ºF Responding variable(s) The variable(s) you are measuring (your data) Controlled variables (these increase validity) Variables kept the same in all trials Ensures that results are due to the ONE manipulated variable Control group The group used for comparison (it has NO manipulated variable) Replicates/trials (these increase reliability) Do everything at least 3 times

Example experiment – Day 1 Example question: What is the effect of caffeine on student heart rate? Example MV: Caffeine Example conditions One cup, two cups, three cups of coffee Example responding variable Student heart rate Example controlled variables Many… Example control group Students with NO caffeine

Example hypothesis If students increase their consumption of caffeine, then their heart rates will increase because I have read that caffeine makes you hyper.

Basic lab setup Materials and procedure covered in “experimental design”

At your desks Determine what chemical you will be testing. Have a volunteer from your group write the chemical on the board. Do question 1, 2, and 3 as a group. Then read the Experimental Design (Part I) carefully. Work on remaining pre-lab questions with your partner. You may work together in class, but work outside of class must be your own (Look at all questions now, discuss answers now…)

Instructions – Day 3 Right now - determine who will read directions. CHECK IN. Materials on lab benches and center table. “Divide and conquer”Divide and conquer I will give you seeds… Use a SMALL amount of blue tape. Label EACH dish with period, table, conc. of chemical. Do not write directly on the dishes. All dishes get 3 mL of liquid. See instructions! Seal your dishes as demonstrated. Wash hands! Dishes - spread out by side of benches, single layer (parafilm) Use ONE pipette for your chemical. Throw away at end of lab. CHECK OUT with me before you leave. See instructions on lab bench. No credit for lab unless you check out.

Instructions – Day 4 CHECK IN AND READ DIRECTIONS FIRST! (Choose your direction-reader now.) Everyone needs a job! The shoot is the portion above the root. Fuzzy hairs = probably root. See diagram.See diagram Measure to the nearest 0.5 mm (e.g. 3.5 mm or 2.0 mm.) Use tweezers, pull off seed coat gently if necessary/possible Record the 5 “shoot lengths” for each trial in the data table. You should have 60 shoot lengths measured. Record average length for all 15 shoots in treatment. Phones ok. Record your results on the board. Check out with about 5 minutes remaining. If you finish early, work on HW questions at your lab bench. Use full sentences if the question asks you to EXPLAIN. Your participation score reflects how well you use your time.

Extra time questions Proposed question: How would student GPA be impacted by requiring all students to attend school for more weeks during the summer? Hypothesis: If students (with low GPA) go to more school in the summer, then their GPA will not change or increase just a little because if it’s low it’s probably because of effort – and they won’t work harder in the summer. Why do we need a control group? What is it? Controlled variables? Be specific Manipulated variable? Why do we use ONLY ONE manipulated variable? Reasonable conditions of the manipulated variable? Responding variable?

Extra time questions