(2)  Scientific processes. The student uses scientific methods during field and laboratory investigations. The student is expected to: (A)  plan and implement investigative procedures including asking questions, formulating testable hypotheses, and selecting equipment and technology;

On the TAKS test, you will be tested over your knowledge of how to design and carry out a scientific experiment.

So what are the steps in planning and implementing a valid experiment?

Dictionary Help: VALID means acceptable, or legitimate, trustworthy.

Dictionary Help: IMPLEMENTING means doing the experiment, taking the steps to make it happen.

Asking questions: Can you look at an experimental set-up and figure out what question the scientist was trying to answer? Look for clues in the drawing or paragraph! What are they measuring? What does the data tell you?

The diagram shows an experimental setup. Which of these questions was this experiment designed to answer?A Does water boil when exposed to air?B Will fire turn a gas into a liquid?C Does air expand when heated?D Will heat turn a gas into a solid?

AirHeat

Formulating Testable HypothesisCan you recognize a valid hypothesis? Can you create one?

Is it a statement that you can prove with data?

Is it testable? What question might these students be trying to answer?

What hypothesis might these students write to test their question?

Is the experiment valid?

Factors affecting the validity (trustworthiness) of the experiment

• A control group is used

• The hypothesis has measurable variables (“Flowers grown indoors will have the ‘best’ smell,” is not a measurable variable!)

• Sample size is large enough. You have to run lots of test over and over again to get reliable results

• Only one variable is tested at a time! “Will limiting sunlight and water effect plant growth?” is not a valid question!

30.The table shows the time it took trees of the same type and size to drop all of their leaves after being grown in different atmospheres. For the experiment to be valid, which of these must be a constant for all the trees?

F The height of all the trees during the entire experiment

G The amount of water available to all trees during the experiment H The mass of fallen leaves collected from each tree

J The rate of photosynthesis in all trees during the experiment

READ CAREFULLY!

Dependent variable

Dependent variable

Dependent variable

All of the independent variables but one (gases added) must remain constant for the experiment to be valid.

Selecting the correct procedure and equipment:

Sometimes you will be asked to select correct equipment or the correct procedure from a particular lab set-up.

Which procedure is best to use when determining the density of a rock?F Place the rock in a water-filled beaker and find the height at which the rock floats above the water.G Use a ruler to measure the rock’s dimensions and then find its mass using an analytical balance.H Measure the mass of the rock on a balance and then find the volume of water it displaces in a graduated cylinder.J Place the rock in three liquids with different known densities and observe which liquid the rock floats in.

Formula Chart to the RESCUE!!!!

1. Melting Point

2. Conductivity

of solution

3. Solubility

Equipment

Your teacher has given you two unknown white solids. Your task is to mass out a sample of each compound for each test and determine the following:

Equipment

Equipment

Procedure

Procedure

Procedure

Procedure:

Heat two grams of each unknown compound to determine the temperature at which they begin to liquefy.

Procedure:

Place two grams of each compound in 18ml of water. Determine the conductivity of each substance.

Procedure:

Measure 10ml of distilled water. Place a two gram amount of that compound into distilled water. Measure the temperature at which it is completely dissolved.

Litmus paper

Hypothesis:

Dependent variable:

Independent Variables:

Question answered in this experiment:

Control Group:

Wavelength (Color of light)

mL of Oxygen Produced in 10 minutes

Sunlight 20Green 3Red 18Blue 16

Controlled Variables:

The picture shows an experiment using different colors of light with elodea plants.

Blue light will generate the greatest oxygen production.

Amount of oxygen gas produced

Length of time exposed to light, type of plant, size of plant

Color of Light given off by the lamp

Which wavelength (color) of light will cause the highest rate of photosynthesis?

Plant placed in sunlight to record oxygen production.

Blue light will generate the greatest oxygen production.

Amount of oxygen gas produced

Length of time exposed to light, type of plant, size of plant

Color of Light given off by the lamp

Which wavelength (color) of light will cause the highest rate of photosynthesis?

Plant placed in sunlight to record oxygen production.

Blue light will generate the greatest oxygen production.

Amount of oxygen gas produced

Length of time exposed to light, type of plant, size of plant

Color of Light given off by the lamp

Which wavelength (color) of light will cause the highest rate of photosynthesis?

Plant placed in sunlight to record oxygen production.

NEED 8 Sheets to make 24 sets!