The electron-positron annihilation and Compton scattering experiments are designed for educational purposes in an upper level modern experimental physics lab. The electron-positron annihilation experiment demonstrates the existence of antimatter and allows for a measurement of the mass of the electron. The Compton scattering experiment demonstrates the particle nature of light. The original setup for these experiments was imprecise, slow, and clumsy to use. We set out to design an apparatus that both improves the quality of data collected and decreases the difficulty in collecting the data. When using the apparatus for the electron-positron annihilation experiment, the number of single photon counts measured over varying distances from the 22Na source was fit to a power function ( a/r^n ), which yielded n = 2.01 ± 0.03. This result agrees with the expected form of ( 1/r^2 ) emitted from a point source. By measuring the number of coincident photons emitted from the source as a result of electron-positron annihilation, we were able to determine the mass of an electron to be me = 510±15 keV/c^2 which agrees with the known mass of 511 keV/c^2. When using the apparatus for the Compton scattering experiment, we performed a linear regression of 1/E’ as a function of (1−cosθ), where E’ is the energy and θ is the angle of the scattered photon. The regression yielded a y-intercept of 1.49 ±0.04 MeV^-1 which agrees with the expected value of 1.51 MeV^-1 and a slope of 1.93 ±0.04 c^2/MeV which agrees with the expected value of 1.96 c^2/MeV . The new apparatus succeeded in providing better results and streamlining the procedure of the experiments.