Short Answer
Erections and ejaculation are normal parts of coed sex education curriculum focused on puberty for puberty-aged kids.
Encouraging students of this age to talk with their parents about what they are learning about puberty and sexuality in school is an evidence-based approach to education.
It's possible this particular assignment was phrased oddly, or that it has been misinterpreted by the parent, but I can not find evidence that the specific assignment has been shared anywhere except the description cited in the answer. However, yes, it seems consistent with the curriculum that students would be prompted to discuss these topics at home.
Longer Answer
This news article: https://caldronpool.com/primary-school-children-told-to-ask-their-dads-about-their-erections-and-ejaculations-for-homework/
has some images of pages from "Victorian Government's Catching On Early: Sexuality Education for Victorian Primary Schools" curriculum, which is purported to be the source of this lesson. I have not found an example of the lesson itself shared by a constituent to the MP, but this is supposedly the source according to a teacher named Moira Deeming, who like the Australian MP is against the sexual health curriculum taught in schools.
The cited images appear to me to be basic diagrams appropriate for a puberty-age classroom about basic internal and external reproductive anatomy. The written pages suggest that students be familiar with the reproductive systems of humans and how they change across the lifespan (keeping in mind that for many 10 year olds these changes are happening to them now or will be in the next year or two). This includes being aware of "real" words for body parts, rather than only slang ones, understanding the purposes for slang terms and appropriateness of slang in different contexts.
These pages do not mention "erection" or "ejaculation", though other pages do. The full curriculum is available here:
https://fuse.education.vic.gov.au/Resource/LandingPage?ObjectId=ee5cfd49-48e7-4698-a06d-37e2e21cbbd9&SearchScope=All
Examples from the curriculum:
Boys get erections from the time they are babies. An erection is when the penis grows stiff
and sticks out from the body. As boys grow older, and especially during puberty, they can
get more erections because they are nervous or excited or it just happens by itself. This can
be accompanied by a feeling of pleasure. It can be embarrassing at first but other people
don’t usually notice as much as the boy does.
This seems to emphasize that erections happen and are normal; that they can be embarrassing but are perhaps less noticeable to others than the boy might think. Importantly, a classroom full of 10 year olds is a classroom where some of the children have already noticed erections, either in themselves or other classmates, during the school day, and almost certainly will in the next year, and perhaps it's good to learn what is happening ahead of time.
For ejaculation, the curriculum mentions it in the context of human reproduction in context of "the life of a sperm cell":
The urethra carries me (along with about 200 million other sperms) out of the
penis in a process called ejaculation.
it also mentions ejaculation among other puberty changes in boys:
Sperm production may begin and about a year after the
penis starts growing, he may have his first ejaculation.
There is also a "puberty cards" section for students to learn to associate particular changes with puberty, and the "boys changes" include cards:
Ejaculation – semen released from penis
and
More erections (penis gets hard)
It seems at least highly plausible to me that a worksheet based on this curriculum might ask students to discuss these things they are learning about at home (ask your moms and dads about...). I think it is important to recognize the context of these discussions: that according to the curriculum they should be age-appropriate, that whatever the developmental level of a given student, there are definitely girls and likely boys as well showing signs of puberty by age 10, and for those who are not yet showing signs they should be prepared to in the next year or two. I think it is also important to recognize that directing these conversations to the home is meant to keep parents involved in what their kids are learning about: "ask your dad about puberty" might make dad uncomfortable, but it's also his responsibility to teach his kids about these things, and parents can answer questions at home in the way they feel is appropriate for their child and may touch on topics their child doesn't feel comfortable discussing in front of a classroom.
I think it also seems plausible that this content may have included the list of changes in boys from this curriculum provided on note cards, which would include:
penis grows bigger, shoulders get wider, wet dreams, start making sperm, ejaculation - semen released from penis, bigger muscles, more erections (penis gets hard), testicles and scrotum get bigger
I could see a parent that felt upset about this curriculum seeing this list and emphasizing "ejaculation and erections". However, it appears that this has been taken out of context into some oversexualized lesson, when it is not at all clear that has happened. Dad should probably be responding by assuring their daughter that yes, these are things that the boys in her class are and will be experiencing (he could even mention that when he was 10 or 11 or 12 that he went through those changes, too, and still survived!), that if she has any further questions about those things or anything that is changing in her body that she should feel free to ask those question to her parents, and that it's okay if those questions come up tomorrow or next week or next month or in a year or two. Dad could also provide some reading on puberty if he or his kid feel more comfortable with that.
Alternatively, he could complain to his MP.
