Planning an Inquiry-based lab

Yesterday, during one of my classes at Co-op, the kids made 'apple mummies'.  The experiment in the Young Explorer Human Anatomy textbook to make a mummy with a mixture of baking soda and salt with one apple, leaving a second as a control.  Fine.  But, this is an opportunity to take an experiment and adapt it for inquiry.  First, the Egyptians used natron, a fact I remembered back when I'd helped the school librarian sponsor an Egyptian camp.  We made orange mummies.  Natron is a mix of compounds and can be approximated with washing soda, baking soda, and salt.  I tossed in Epsom salts for our lab.  Since natron is a mixture, it would be logical to test a similar mixture.  But how would you determine if the individual compounds might also work?  Which combination?  See where I'm heading.

Here's what we did.  This class has five home-schoolers, aged 6-11.  Together, we determined the supplies.  I set the total mass of compounds at 60 grams.  On a blackboard, I drew cups, labeled the compounds by their names and assigned numbers: 1. washing soda, 2. Epsom salts, 3. Baking soda, and 4. table salt.  Cup 5 is the control.  Under this row, I drew another row of cups and walked the kids through  two different combinations of compounds: 1+2, 1+3, 1+4, 2+3, and 2+4.  In the third row, I drew another series of cups with three different mixtures: 1+2+3, 1+3+4, and 2+3+4.  After a minute to explain the mixtures, the kids dispersed to weigh, mark cups, locate the different chemicals, and trouble shoot.  We decided to weigh the apples and write their respective masses on individual cups.  This takes time.  We made sure everyone had a chance to weigh with a digital balance using the tare button.  After, the kids noted their predictions regarding which mixture would dry the apple most and copied the blackboard into their notes.  Next week, we'll look at the mummies and weigh the apple pieces.  Finally, we'll look at their predictions to see if the evidence supports or refutes their hypotheses.  Yes, this is a lot more work.  The result is a lot more science.  This apple mummy lab is similar and can be adapted to add more salts.