Ask a Question How does fertilizer affect the growth rate of plants? scientists notice something in their natural world Example: Does fertilizer make plants grow taller?
Make Observations Gathered using the 5 senses Record what happens during the experiment in your lab notebook Use black or blue ink The information you write down is called data Example: My neighbors’ plants are taller than my plants. He uses fertilizer and I do not.
State a Hypothesis A suggested solution to the problem Must be testable Sometimes written as If…Then statement Predicts an outcome Example: If plants are grown using fertilizer, then they will grow taller.
Design an Experiment A procedure to test the hypothesis set up an experiment testing different amounts of fertilizer on plants & measuring the growth (height) of the plants must contain variables and controls may have many controlled factors can only change one variable
Design an Experiment Controls factors that are kept constant not being tested! examples: amount of water, type of soil, amount of sunlight, type of fertilizer act as a standard of comparison should not effect the outcome of the experiment
Design an Experiment Variables 2 types 1- dependent variable what you measure in the experiment unpredictable change: we don’t know how it will change until we do the experiment graph on Y-axis height of plants 2- independent variable manipulated variable predictable change: it only changes because we chose how it would change the more trials… the better graph on X-axis amount of fertilizer The effect of _____________ on _____________ INDEPENDENT DEPENDENT The effect of _____________ on _____________ Amount of Fertilizer Height of Plants
Collect and Analyze Data May be organized into charts, graphs, tables 2 types of data Quantitative Expressed mathematically numbers Qualitative Descriptive nature words, feelings
Analyze Data What does your data show Graphs line graphs graphing data that shows continuous change bar graphs (or histograms) graphing data that is in disconnected groups How’s a critter to choose?
Examples of experiments What’s the favorite drink of students? we set up an experiment surveying students and asking which is their favorite drink : dependent variable (Y-axis)? number of students independent variable (X-axis)? type of drink The effect of _____________ on _____________ Type of Drink How many students chose it
Which drink do you like best? type of drink number of students 1 2 3 4 5 6 CokePepsiwaterteaGatorade 0 drinknumber Coke1 Pepsi1 Water4 Iced tea4 Gatorade3 Red Bull? RB Bar graph!
How does elevation affect temperature? elevation temperature 5 10 15 20 25 30 05001000150020002500 0 elevation (feet above sea level) temp. (°C) 030 50025 100020 150015 200010 25005 1200 ft? 1818 Line graph! 1200
Form Conclusions Answer to the hypothesis based on the data obtained during the experiment Check for bias In order to verify the results, experiments must be Retested valid! Communicate results Scientists publish work in journals
Examples of experiments How does exercise affect heart rate of 10th grade student? we set up an experiment testing different lengths of time of exercise (minutes) on the heart rate of students: dependent variable (Y-axis)? heart rate independent variable (X-axis)? minutes of exercise The effect of _____________ on _____________ Exercise Heart Rate