Scientific concept: Cellular respiration oxidizes organic chemicals and releases CO2 into the environment and photosynthesis converts CO2 into fixed carbon in the presence of light.Irrespective of the light conditions, respiration in live cells in the beads will release CO2 that will dissolve in water inside the bracelet\/necklace in which the beads are immersed to generate carbonic acid. Conversely in the light, photosynthesis in the algal cells in the beads will remove CO2 from the water surrounding the beads. Hence pH of the water inside the algal bead bracelets will be acidic in the dark and alkaline in the light. Students can monitor the dramatic color changes in a gradient fashion in the water inside the bracelet that is induced by the relative rates of photosynthesis\/cellular respiration. Students can measure pH of the water inside the bracelets\/necklaces using pH testing strips. This protocol might be also useful for bioenergy researchers who are interested in exploring the use of immobilized motile micro-algae for biofuel production. Applications:This educational protocol can be used to teach the interplay of photosynthesis and cellular respiration to K4 - college Biology students in a fun and engaging way. The lab activities can be customized according to grade levels. Students will make their Chlamydomonas beads and use these beads to make algae bead bracelets or necklaces to test the opposing nature of chemical reactions of cellular respiration and photosynthesis. This interplay can be studied by visually monitoring the water color\/pH changes induced by relative rates of photosynthesis and cellular respiration under light and in darkness. Alternatively, this protocol can be used by educators at institutions with limited resources who do not have access to an oxygen electrode to comparatively study relative rates of photosynthesis in Chlamydomonas wild type and a photosynthetic mutant strain using strain specific-algae beads that approximately the same number of cells per bead.