At the 9th grade level, biology typically deals with topics like plants, animals, ecosystems, and internal systems; however, honors students may tackle advanced topics like cell biology and evolution. One idea for a 9th grade honors biology project is to test the effects of different fertilizers on the growth of plants. In this project, you grow plants in five different pots and use different fertilizers in each, measuring the plant's growth once a day using a ruler. Another idea for a 9th grade honors project is to evaluate the factors affecting the growth of mold. In this project, you leave pieces of bread out under different conditions: in the fridge, in the basement, in a kitchen cupboard. You then measure the mold growth day after day by measuring the width of each mold dot with a ruler.
Chemistry is the study of the physical building blocks of the universe. Ninth grade chemistry typically covers topics like the periodic table and basic chemical reactions. One idea for a 9th grade chemistry project is to measure the pH of rural lakes compared to urban lakes in your area. In this project, you simply collect water samples from rural and urban lakes in your area, then put a piece of blue litmus paper in each sample. If the litmus paper turns red, the water is relatively acidic; if the litmus paper stays relatively blue, the water is fairly basic.
Physics is the study of matter, motion, energy and relationships between these properties. At the high school level, physics is a fairly math heavy subject. Ninth grade honors projects in physics may draw on 10th or 11th grade math, or may focus on novel aspects on of 9th grade physics topics. One idea for a project that does both is to fire a rocket, using math to estimate the trajectory of its path. Buy a small, non-flammable rocket at any scientific or hobby supply store, shoot it off, then graph the trajectory of the rocket by dividing altitude, velocity and mass by time. Record the actual trajectory of the rocket on video camera, and compare this to the graph you produced.
Technology is not strictly a scientific topic; however, advanced technology projects are generally accepted at science fairs. If you have any special skills, like programming or woodworking, you can showcase these skills in your 9th grade science project. One idea for a 9th grade technology project is to build a bicycle with a motor on it. To execute this project, you need to cut the bottom bar of your bike off and then weld it back on at a lower level, which you will need to do with proper protective gear and under adult supervision. Once you have done the welding, attaching a motor is as simple as attaching a chain connecting a small dirt bike motor to your bike's back gears.