Science GCSEs - how hard are the Unit 3s?

[RedValerian]

DD is in Year 11. They took their Science unit 1s last summer, then the unit 2s in Jan. As soon as the Unit 2 results were out, the school told anyone who had 'only' got a grade c in the Unit 2s that they would be put in for Foundation level for Unit 3 'to maximise the chances of an overall grade C' - even if they had b or above in Unit 1 / hadn't misssed out on a b by much in Unit 2 and had a good ISA mark. Are the Unit 3s really much harder? Or is there some other explanation?
Since the number of UMS points are the same for each module, I would expect them to be equally difficult- which would mean that borderline students are being denied a chance of getting a B grade.
The board is AQA, if it makes a difference.
TIA

Hi. My DD is taking unit 3's AQA this summer. From the revision she is doing it doesn't look harder. Her school definitely don't have this policy. Anyone who got lower grades than expected in unit 1 or 2 are encouraged to resit the modules.

Not harder. But grade boundaries are proving unpredictable, so I suppose they are erring on the side of caution.

the head of science told me that ds3 who is doing double ie 1&2 then 3&4 will actually be covering much of what ds1 did in unit 5 for his triple 3 years ago as a lot of the material has moved to unit 3. Its the chemistry element that seems to have got a lot harder apparently. Thats OCR though so AQA may be different

Assuming the UMS is still 100 for each paper and the ISA (as it used to be), and lets assume a mid B for the ISA and paper 1 (75 UMS each) and a high C for paper 2 (68 UMS), that makes 218UMS already. Since a C grade is 240/400UMS that only leaves 22UMS to gain on the last paper for a 'C', so I think the school is being over cautious. However, the max UMS at foundation level would be 69UMS which would give 287/400 and an overall B, so I think it is an A grade that is being denied here and the probability of that is very slim (in fact, not possible with the numbers given as would need 102UMS on the last paper), so it really comes down to whether 60something UMS is easier to achieve on foundation or higher and to be fair it probably is easier on foundation.

Unit 3 knowledge really builds on the knowledge from Unit 2, not totally but quite a bit. So that could be the thinking behind it. If pupils don't have a firm grasp of Unit 2 they could find it harder to grasp Unit 3.

The school will have a pretty good idea whether a B+ grade is possible based on all the banked marks so far. If not, and C is the best grade possible, then the school should pick the tier best suited to each child for them to nab a grade C overall.

The problem with higher tier is that it's taken by the bright students and although not so many marks are needed to get to the C grade you cannot afford to make mistakes on the easier questions as there aren't many of them. It can be easier to fall off the scale on a higher tier paper.

My son has UMS 73 on paper 1 and 2 (grade B's), and circa UMS 65-70 (a guesstimate mid/high Grade C) on controlled assessment. He is therefore very borderline B/C and needs higher tier to give him a chance of nabbing a B overall after sitting paper 3. I don't think it is even mathematically possible for him to get an A. The school should do all of this calculations and work out the best tier to sit - just ask them how it works, our school is really helpful.

Thanks for the replies. I am reassured wrt how difficult it will be. I'm amazed how complicated it is though.
Fortunately, she is revising hard, so I hope it will all work out well!