Estimating provides great opportunities for thinking about numbers without the fear of being wrong, as an estimate is different to calculating an exact answer. Estimating is different to guessing as it involves applying existing knowledge. You may randomly guess the number someone is thinking of, but you would estimate there age (probably very cautiously!) based on their appearance in comparison to others whose ages you know.
The following estimation activities involve lots of opportunities to ask questions and share mathematical thinking in a fun practical way.