NRICH has designed tasks which show how maths is used in other subjects and which provide authentic contexts in which students can use their maths.
However there are many legitimate concerns which you may have about increasing STEM in your classroom.
You may be worried about:
being expected to teach outside your standard subject knowledge
not being an 'established expert' - feeling deskilled
pupil inertia and disjointed '50 minute' thinking.
both teachers and students feel they have to 'know' the answers or know exactly what to do before feeling safe and comfortable
that cross-curricular coordination is needed to provide links across departmental SoWs, eg Y9 are taught the parallax error months before maths has covered any trigonometry
possible differences between exam boards' specifications at KS4 as to content relevance
needing maths in SET (eg time, reading scales) which was supposed to be covered at primary school
assumptions that certain concepts and content are being covered 'elsewhere'
changes in exam syllabuses
differences in 'abilities' or interests of students in different STEM subjects - DT often taught in mixed ability groups, where maths and science are set, maths and science sets may not be the same
different teaching groups for maths, science and technology lessons.
timetabling and matching topics across subject areas
ease of communication between staff, especially if there are separate departmental staffrooms
some key teachers being resistant to change or sceptical about the value and importance of the 'other' subject(s).
timetabling making planning meeting difficult.
needing specialised equipment or technology for STEM lessons
funding - for resources, for time to meet, ...
finding time to talk to other STEM colleagues
physical location of necessary resources in large school
differences in time allocated to matching topics across subjects.
students complaining that they've done something before in another subject
students claiming 'This isn't maths!' or 'This isn't science!' or 'We don't do maths in DT!'