Research science basics at your local library. If you are not working with a set curriculum, you can find plenty of science material at the library or on websites. If your child is in high school, you can use online classes or try local college science departments for help.
Go outside into your yard or local park for some science instruction. Growing plants from seeds in soil and a pot is a good start in learning biology, and you can also learn about nutrition. You can work with your child in identifying plants and animals in your neighborhood. Together you could research the native flora an fauna online.
Visit your city's zoo or science museum. Ask your child which parts of your field trip interested her and work on a project together. Home-schooling can be very individualized and your child can choose what to study in depth. Create a project around the area of science she is most interested in. For example, if she likes flowers, she can start a botany or genetics project.
Work with a local home-schooling group. Many groups get together and work on group homeschooling lessons. Together you may be able to construct a science project that is age-appropriate and correlates to what you have been teaching your child.
Purchase some science equipment, like a microscope, to spark interest in your child. Find different things around your home to look at through your microscope. Later, your child can grow bacteria or mold to examine under the microscope.