Hay Infusion Lab
Part 1
Names________________________________
_________________________________________
Purpose : You will design a Controlled Experiment. You will put grass and water
into a container and observe over a several days as bacteria and protists start to
appear. You will test a real world situation and observe what happens to the
number of organisms.
Examples of dependent variables to test: darkness, liquid fertilizer, sugar, salt,
and lemon juice.
What is the dependent variable your group will be testing? ________________
What is the independent variable in this experiment? _____________________
Control Variable: Every group will be comparing their dependent variable to a
control variable.
Questions
1. What will be in the flask of the control group (no dependent variable)?
2. How is the experimental group (dependent variable) different than the
control group?
3. Write your hypothesis for this experiment. Use the “If…, then…” format.
_________________________________________________________________________________________________
_________________________________________________________________________________________________
Materials :
2 Plastic cups
Hay (grass either green or dried)
Tap water
Other Materials Your Group Needs:
__________________________________
___________________________________
__________________________________
___________________________________
Procedure:
1. Label your plastic cups with the names of the members of your group and
#1 control and #2 dependent variable.
2. Fill each cup ¾ full with hay.
3. Add water to the top of the hay.
4. Add your dependent variable to cup #2. How much will you add?
___________________________________________________________
5. On what date will we check our hay infusions (ask Ms. Swedmark)?
_______________________________
Further questions:
1) What is the purpose of a control group?
2) List the steps of the Scientific Method in order.
a) _______________________________
b) _______________________________
c) _______________________________
d) _______________________________
e) _______________________________
f) _______________________________