The outer tube has slots which match the compartment openings of the inner tube. When the slots are aligned, grain can enter into and be emptied from the compartments. This activity will use plastic drinking straws instead of metal to construct model probes for testing sample containers of rice or other small grains. Teacher should construct at least one sample probe to show the students and to determine the optimum size of the sampling window. Your key could also include the economic implications by listing the expected price per ton of grain of different grades.
Teacher prepares some practice samples illustrating the basic concepts and use of the sampler.
Practice samples should be in visible tubes so students can observe the sampling process and make design changes to their sampler if needed. These sample should be similar in general nature to the practice samples, but masked off in some way so students can only see the tops of each container. Also, during your prelab, decide on how many samples you would expect from each student to earn full credit. Simulate real world situations by making representative mixtures. This window should be large enough to allow rice or other sampled grain to freely enter the window.