Online textbooks for Science are available here:  www.pearsonsuccessnet.com
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Online textbooks for Math are available from Math teachers.
If you are trying to obtain an additional copy of a textbook on your own, here are the titles and ISBN numbers.  They are often available for sale on Amazon or elsewhere as used copies.
Comprehensive Textbook List
 Subject  Title  Publisher ISBN 
 7th Grade Social Studies  World History: Medieval to Early Modern Times  Holt 0-03-073399-5
 8th Grade Social Studies  United States History: Independence to 1914  Holt 0-03-041228-5
 7th Grade Science  California Focus on Life Science  Prentice Hall 0-13-201272-3
 8th Grade Science  California Focus on Physical Science  Prentice Hall 0-13-201270-7
 7th Grade Language Arts  Writing and Grammar, Bronze Level, Handbook Ed.  Prentice Hall 0-13-037313-3
 7th Grade Language Arts  Literature: Timeless Voices, Timeles Themes, Bronze  Prentice Hall 0-13-054803-0
 8th Grade Language Arts  Writing and Grammar, Silver Level, Handbook Ed.  Prentice Hall 0-13-037343-5
 8th Grade Language Arts  Literature: Timeless Voices, Timeless Themes, Silver  Prentice Hall 0-13-054804-9
 Math 7 Core Connections:  Course 2 CPM 978-1-60328-0846
 Advanced Math 7  both Core Connections 2 and 3    
 Math 8  Core Connections: Course 3 CPM 0-978-1-60328-091-4
 Advanced Math 8  both Core Connections 3 and Integrated 1  CPM 0-978-1-60328-323-6
 Algebra 1, 1st semester  Algebra Connections, Vol. 1, California Edition  CPM 978-1-60328-009-9
 Algebra 1, 2nd semester  Algebra Connections, Vol. 2, California Edition  CPM 978-1-60328-010-5
 Geometry 1st semester  Geometry Connections, Vol. 1  CPM 978-1-931287-58-6
 Geometry 2nd semester  Geometry Connections, Vol. 2  CPM 978-1-931287-59-3