Boys invited to a secondary school event were sent to technology classes while the girls learned about cooking food.
Parents have reacted with fury to the sexist attitudes at the schools, which were holding taster sessions for primary school pupils from the area.
The Year 4 girls visiting the school to get a sense of secondary school life took part in high school food technology and drama lessons.
The boys all did design and technology classes arranged by the grammar school instead.
Details of the day were released in advance through a letter sent to the children’s parents, LincolnshireLive has reported.
One angered parent said: "I think this letter, which came home with an upset nine-year-old girl today, shows that as a country/society, we have not progressed one centimetre in 30 years.
"She lives and breathes design and technology and can't understand why she has to do cooking and drama.
There was also an outcry on Twitter after the gender split became public.
One Twitter user wrote: "Was this letter sent out in 1819? Sounds like someone at school needs to reconsider, speaking as someone whose wife is a successful engineer and who has four daughters."
Another user said it reminded them of their time at school when they were a child.
"As a girl in primary school in 1969 I had to do embroidery while the boys got to play football at the rec. I feel her pain," she wrote.
Others said it was unfair on both girls who wanted to do woodwork and boys who wanted to do the other subject.
"I am livid on your behalf and for all the girls, and also for the boys who might fancy a bit of cooking. They should all be doing both," they wrote.
One social media user said the children might have already been given an experience of sorts.
They wrote: "Well that's been an unfortunate and antiquated learning experience already. Suggest taking a day off to visit some heavy engineering at Denver sluice, Salters Lode and Prickwillow museum instead."
In a joint statement, Spalding Grammar School and Spalding High School defended the scheme, saying its intentions had been "misinterpreted".
"As part of a broad Primary Liaison programme, helping primary school pupils to transition confidently to secondary school, Spalding Grammar School (for boys) and Spalding High School (for girls) work together to provide a range of experiences, including an opportunity for local pupils to spend part of a day with us," they said.
"Across the last 10 days, we have welcomed over 700 pupils from 24 schools, and they have experienced the full range of subjects available at both schools. The actual subjects offered on any given day are simply dependent on the availability of staffing and resources.
"We have received, as we do every year, a huge amount of positive feedback about this initiative and it is a shame that our intentions have been misinterpreted in this way."
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