Checkpoint: changes that make nothing new

A sheet is folded three times the same way. Then it is cut straight across. How many pieces?

• 2, because one cut makes two pieces
• 9. One cut through eight layers makes eight cuts
• 4, because that is three folds and one cut

200 g of ice melts. Then it all boils away in a closed pot. What does the steam weigh?

• Less than 200 g, because steam is light
• 0 g, because a gas has no weight
• 200 g. Nothing is made and nothing is lost

Two spoons of sugar are stirred into a glass. It looks clear. Where is the sugar?

• It has turned into water
• It is in a layer at the bottom that you cannot see
• It is in pieces too small to see, spread through the glass

A clay pot breaks into nine pieces. Which is true?

• Nothing new is made, and glue does not bring the pot back
• A new substance is made, because the pot is gone
• No new substance is made, so glue gives the pot back

Which is a physical change that cannot be undone?

• A chalk stick ground to powder
• Sugar dissolving in water
• Ice melting in a glass