More evaluations of ELIs

The following are more evaluations from workshops held in New Mexico. 
Rock, rattle and roll
We set up a ‘competition’ by asking for a prediction of which rock would erode most easily.  The two students made different choices.  As one of the students noted: It opened the door for a quick mention of experimentor bias.
Suggestion:  Begin with the rocks that are not going to erode easily and work your way to the ones that do.
Make your own rock
- We had a difficult time getting the sugar and salt cemented sediments to dry out.  We did heat them slightly but they were still damp at the end of the week.  It did open a discussion of why they did not work and how to improve the activity.
- The salt and sugar used for the other rocks did not really keep the sand together so we were not able to test them by dropping a ball bearing on them.
Suggestions: Be very specific on the amount of ‘cement’ to put into a cup.
… have other materials to make rocks out of.  Make one with white glue (Elmer’s glue is the common brand here in the States) and another with candle wax.
What was it like to be there – in the rocky world?
I liked being able to visualize the environment by looking at the rock.
Suggestion:  Students could write a story or essay about the environment that rock was in.
From an orange to the whole Earth
- realized that one object can be made up of layers with different density.
- the model also helped to visualize the Earth is made up of layers of different density.
From clay balls to the structure of the Earth
- The models built by the class did not work as well as expected.
Need to have a larger variation in weight between the two balls.
- Thinner layer of clay over a larger weighted center in order to be able to test with a magnet.
Magnetic Earth
We used a magnetized needle instead of a “magnaprobe.” The group struggled to understand the instructions.  I believe that part of the problem is because they truly do not understand the magnetic field; they could not adjust or adapt and did not understand the instructions. With guidance the students did locate the poles and the equator.  We then lightly marked those on the clay ball.  We had less success trying to measure the angles between the equator and poles.
- Directions were very confusing and took the entire class to figure out how things should look.
Suggestions: 
Better directions, more visual pictures and diagrams.
Use the diagram from activity Frozen magnetism.
Frozen magnetism
- The way the iron filings stuck out of the wax really showed the effects of the magnet.
- Magnetic field is seen 3 dimensionally.
- Was very well written and easy to understand.
Partial melting
The wax was a neat way to show how solid rocks when heated can become liquid and then cool and separate from the rocks that did not melt.
Learned a lot about the melting points of different rocks and how that affects what we find on the surface of the Earth today.
The continental jigsaw puzzle
Hands-on activity that really allows the students to learn by trial and error.
Magnetic stripes
When doing this activity referred back to Frozen magnetism.  This was when students had more questions and were trying to put it together and began to understand why magnetic stripes are important.
- Learned how rocks retain their magnetism long after they are formed and even after the poles have changed.
- During this activity we were able to see that as the magnetic fields arise they also change polarity from north to south.  Still some misconceptions….
- I learned more about magnetic alignments in rocks of the ocean floor.  The magnetic field has been reversed in Earth history and rocks still bear the magnetism from when they first formed. 
Suggestion: A step-by-step instruction for the construction of the model.  The illustration or diagram is not adequate.
If you have comments and suggestions about Earth Learning Idea activities, then please let us know.