Recent years have seen the evolution of networks of tiny low power computing blocks, known as sensor networks. In one class of sensor networks, a non-expert user, who has little or no experience with electronics or programming, selects, connects and/or configures one or more blocks such that the blocks compute a particular Boolean logic function of sensor values. We describe a series of experiments showing that non-expert users have much difficulty with a block based on Boolean logic truth tables, and that a logic block having a sentence-like structure with some configurable switches yields a better success rate. We also show that a particular use of color with a truth table improves results over a traditional truth table. Categories & Subject Descriptors H5.m. Information interfaces and presentation: Miscellaneous. General Terms Design; Experimentation; Human Factors Keywords Sensor networks; Boolean logic; embedded computing systems; truth table; eBlocks