Growing Germs on Potatoes

Germs go from invisible to visible for Zack and Austin as they watch germ colonies grow on potatoes.

They collected germ samples from these sources:

1. Duck pond
2. Toilet
3. Kenzie’s bowl
4. Austin’s feet

They tested these cleansers:

1. Bleach (4.7% solution)
2. Simple Green (10% solution)
3. Vinegar (100% white vinegar, 5% acid)
4. Tea Tree Essential Oil (2% solution)
5. Urine (100% Baby Scientist urine a.k.a. pee pee)

View the Google Spreadsheet for details of the results.

Hand-Powered Elevator

Zack and Austin built a hand-powered elevator with their dad’s help.

Materials:

• 50 feet of 3/8 inch rope
• 2 pulleys for 3/8 inch rope
• Platform
• 2 8-foot lengths of  1-inch PVC pipe
• 4 strong stakes
• Threaded hook
• Counter-balance weight (bag and cinder blocks)

Equipment:

• Power drill
• Sledge hammer
• Sawzall

Science Principles and Terms:

• Simple Machines
• Mechanical Advantage
• Pulley
• Lever
• Wedge
• Screw
• Forces
• Tension
• Gravity
• Counter weight/Balance
• Bar linkage