Unit 1

1 The Earth

1-5 

6-10 

11-15 DCCAA

16-20 AEACB

2 The Atmosphere

1-5 CEADC

6-10 DBACE

11-15 AEDBB

16-20 DCACA

3 Global Water Resources and Use

1-5 CACEC

6-10 DADDA

11-15 DCCDD

16-20 ACBCA

Unit 2

4 Ecosystem

1-5 DCDDE

6-10 BCCBE

11-15 EBACD

16-20 DDBBC

5 Biogeochemical Cycles

1-5 CBDBE

6-10 AEDAB

11-15 DBBBB

16-20 CBDDA

Unit 3 Population

6 Populations

1-5 ADADC

6-10 ACEEB

11-15 BDAEC

16-20 ACADB