Consider the 3 stages of the ARM7TDMI pipeline (here instruction always refers to the 32-bit ARM instruction that is most relevant for that stage of the pipeline):

Fetch describe what this stage means using the following terms: program, memory, instruction, and instruction register

Decode describe what this stage means using the following terms: instruction, control bits, data path

Execute describe what this stage means using the following terms: registers, ALU, data path