The one thing I learned  in this chapter was bridge makers put joints in bridges so when it gets hot and cold it can expand and contract when it is hot and cold.Another thing I learned in this lesson is when something is hot it expands,and when something gets cold it contract but not ice.One of the favorite things we did is the balloon lab.What does a brick do if you put it out on the the hottest day of the year.         (91 degrees)   will it expand,contrast or neither?