Reassemble the core on a sheet of white paper, making sure that the edges slot together.
Mount the core to a piece of heavy, corrugated cardboard.
Make sure that the wood fibers are oriented perpendicular to the field of view.
Use water-soluble glue to attach the core to the cardboard piece. While drying, firmly keep it in place using scotch tape.
Measuring the tree's age
Count the number of rings visible. Rings are characterized by a light part on the inside and a dark part on the outside. This renders them more visible.
Use diameter of tree to figure out if the core has reached the center of the tree (marked by a oval shaped ring). If not, then determine the average number of rings per inch, and extrapolate in order to figure out how many rings would approximately be in the remaining space. If you had to do this, then mark on the data sheet.
Put a ruler next to the core.
Measure the distance between rings, and record on data sheet.
Compare this data to that of other tree cores to find out more precisely which year each ring was formed (this is known as cross-dating). This is best if done with at least one core that reached the center.
-More specifically, compare the number of rings and look for specific patterns across the cores such as a narrower band of rings. This should allow comparison of age, and can increase the accuracy of the approximate age given by counting tree rings (approximate due to false or missing rings).