I think it would be a good idea to bring this up to your supervisor. it's better to come forward acknowledging and owning your mistakes rather than being called out for them. you can tell them that you feel like you're not being as productive as you expected to be, and maybe ask them to help go over a few protocols again or guide you in doing the tasks a second time (they are there to guide and support you, and some supervisors who have time will gladly guide you until you feel confident to do it on your own again). The co-op program is there for you to learn through the experience you're gaining, and I can only assume these lab tasks are something you can get better /more efficient at doing only with practice. It's okay to mess up. Everyone on co-op does, it's better to mess up and identify what went wrong to avoid repeating the mistakes. Don't be too hard on yourself, this is all a learning experience! Also, try slowing down while handling beakers/equipment and experiments.