Ward's World Activity Guides

Page 2 + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com Find materials for this activity at wardsci.com. Discover more free activities at wardsworld.wardsci.com Investigating Magnetic Forces & Force Fields: Building A Compass Submitted by: Rob S. Background Information, Activity Setup: • The NGSS standards MS-PS2-3 & MS-PS2-5 lead students to "determine the factors that affect the strength of magnetic forces" and "provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact with each other." • This activity shows factors such as the material used in creating a compass needle as well as demonstrating that the Earth's magnetic field exerts a force on a compass needle through field lines extending many miles from the Magnetic North Pole. • See "Step-by-Step Procedure" section below for more activity set up details! Step-by-Step Procedure: 1. Each group will receive one "container of water," one bar magnet, 4 directional compass materials, & one floating device (see supplies for choices). 2. Take one of the four compass needle materials. Rub/stroke the tip of the metal "needle" in a single direction across the North pole of the bar magnet. Be sure students are lifting the "needle" off the magnet and returning it down to make contact each stroke. 3. Stroke the "needle" approximately 10 times (ensure the same number of rubs each group; each type of material as a control for comparison). 4. Place the flotation device (see supplies) in the center of the container with water. Water levels should be just enough so the flotation device (cap, etc.). 5. Balance the "needle" that was just rubbed and center it on the flotation device. The needle should not touch the walls of the container. 6. Identify directional North in your classroom. After several seconds, the needle should slowly spin on the flotation device and point towards "geographic north." 7. Ensure nothing electronic is nearby as the devices will interfere with the compass needle. 8. Repeat for the other materials serving as needles. Students may use quantitative observations as to the effectiveness or strength of the compass. A rubric can be created as a class or by the teacher to rate the "strength" (i.e. 4, 3, 2, 1) or approximate "time" it takes to point north. 9. (Advanced students may even place the compass needle that was rubbed pointing to the east or west direction and time how long it takes for the needle to turn to the north. Data may be averaged for each "needle" material and compiled within classrooms as for the whole grade) Expected Results: Students will see that the materials with the higher iron content will serve as better compass needles. The strength of the bar magnet used to rub the different "needles" will be a contributing variable in the compass' effectiveness. Average iron content for each of the materials can be quickly researched for discussion purposes as well. Teaching Notes: • Students will need to clean up materials in an orderly fashion. It is suggested that the teacher or student leaders move around the room to distribute materials due to the "pokey" nature of the compass needles. • Water will need to be wiped up on occasion or simply provide paper towels to dry off materials each class period. • Data can be compiled on a shared Google Sheet for ease of compilation and discussion.

• Cover