Computer Science is about algorithms and not (strictly) about computers (and electronics).
As such, study of algorithms (even of elementary arithmetic) can bring about understanding of computer science and programming. Remember that even term "algorithm" is a paraphrase of the author of an arithmetica book (al-Khwārizmī, circa 9th cent. CE).
Study of algorithms can be done using elementary means, but should provide coverage of why the algorithm works, how it came about and how can one actually demonstrate that it works correctly.
Thwe history behind the evolution of computer science and algorithms and programming is not to be underestimated. For example, Babbage's/Ada's calculator, Enigma machine, Konrad Zuse's plankalkul, ENIAC etc.
Then one can introduce programming (and programming languages) as a way to formalize algorithms. This can also be done (to a large extend) using elementary means.
Note, some studies have shown that peole learning programming have two main difficulties in understanding (related to the overloading of symbols for example asignment vs equality test and the operation of a RAM machine).
- Loop constructs (e.g for, while etc..) seems difficult
- Assignment vs equality testing, seems also difficult.
So one can make sure these are clearly grasped and understood by the people.
Moreover if any computer can be accessed (even a calculator which can be programmed), this can be used to provide application examples and hands-on experience. Else one can use a simulated computer. This can be done in various ways, for example a group of people can simulate parts of a computer and the class can design algorithms to solve various problems for this simulated computer and see how it goes. This can be seen as a game also, be creative and make-do.
Then some (abstract) computation models (for example Turing Machines) can be introduced and related to the previous material on algorithms and the formalisatinn into a (programming) language.
If one wants to introduce the electronics of an actual computer this can be done also in two parts.
Remember that even in universities some electronics and computer architecture courses are theoretical (one does not actually come into contact with a CPU or design one).
So some principles of operation of electronics (and the underlying physics) related to computer architecture can be introduced (semiconductors, solid-state energy zones, p-np gates, etc.).
Then one can leverage the previous material about programming and algorithms and introduce (modern) techniques of CPU design (and description) which are used in the industry (Logic gates, Flip-Flops, FPGA, VHDL, CMOS circuits etc).
This can be taken further into, CPU design architecture issues like parallelism, pipelining, cache memory, vector adressing, micro-programming, DMA, etc..
Well, ok maybe this can be too much, but added for making the answer self-contained.