Wales Under 18 will play Leicester Tigers Academy in a warm-up game tomorrow (Tuesday, 12 February, 2.30, also at St Helens) in preparation for the Tests against France and England.
Lewis said: "In France and England we are playing two of the major powers in age group rugby so it will be a great test of where we are."
Lewis, who is WRU National Academy coaching manager, has implemented a playing philosophy at Under 18 level which prioritises attacking rugby above all else.
"As a management team we started identifying players very early this season which gave us the chance to watch a lot of Regional and Colleges League rugby, which reinforced what we were seeing at our National training camps," he added.
"Challenging the opposition with the ball in hand is a real priority for us at this age group, we are encouraging these players to use the kicking option as a last resort in order to improve all-round attacking skills.
"The likes of France in particular, and England are able to play either kind of rugby - ball in hand or a more forward orientated game so these matches will be an excellent yardstick for us.
"We are pleased with the development of this group of players, both individually and collectively but you only really get an accurate assessment from seeing how players react to a match situation and that's where the Leicester game will help on Tuesday, and obviously the forthcoming international matches themselves."
With the likes of Tom Prydie, Geroge North and Harry Robinson having stepped straight into Warren Gatland's national squad from Wales Under 18, Lewis is travelling to Japan with Robin McBryde's Wales coaching team in June in an observational capacity.
"We are working closely with the national coaches to ensure we pass their philosophies and practices straight down to our Under 18 players so that the transition to the senior game is as smooth as possible," Lewis said.
Wales Under 18 squad:
Forwards: Callum Mitchell (RGC / Llandrillo College / Colwyn Bay), Alex Jeffries (Dragons / Coleg Gwent / Newport), Ryan Elias (Scarlets / Bro Myrddin / Carmarthen Athletic), Torin Myhill (Scarlets / Coleg Sir Gar / Burry Port), Javan Sebastian (Scarlets / Queen Elizabeth High / Carmarthan Athletic), Liam Belcher (Blues / Porth County Community School / Treorchy), Dillon Lewis (Blues / Ysgol Gyfun Garth Olwg / Pontypridd), Josh Helps (Scarlets / Dyffryn Taf), Adam Williams (Ospreys / Olchfa Comp/ Swansea Uplands), Adam Beard (Ospreys / Neath College / Birchgrove), Rory Thornton (Ospreys / Gower College / Bonymaen), James Sheeky (Blues / Coleg Morgannwg / Glamorgan Wanderers), Michael Snook (Blues / Llanishen High / Llanishen), Oliver Griffiths (Dragons / Coleg Gwent / Crumlin), Will Boyde (Scarlets / Coleg Sir Gar / Narberth), Callum Davies (Ospreys / St Josephs / Tonmawr), Ollie Hitchings (Blues/ Cowbridge Comp / Glamorgan Wanderers), Tom Phillips (Scarlets / Coleg Sir Gar/ Llangennech)
Backs: Gareth Rees (Scarlets / Coleg Sir Gar / Ammanford), Tom Williams (Blues / Treorchy Comp / Treorchy), Dan Brooks (Ospreys / Llandovery Coll/ Bonymaen), Jack Maynard (Scarlets / Coleg Sir Gar), Angus O'Brien (Dragons / Caerleon Comp / Caerleon), Luke Price (Ospreys / Maesydderwen / Abercrave), Daniel Jones (Scarlets / Queen Elizabeth / Carmarthen Quins), Tyler Morgan (Dragons / Coleg Gwent / Caerleon), Craig Woodall (Scarlets / Amman Valley), Joe Thomas (Ospreys / Neath Port Talbot Coll / Morriston), Garin Smith (Blues / Pontypridd High / Pontypridd), Josh Adams (Scarlets / Coleg Sir Gar / Pontyberem), Dafydd Howells (Ospreys / Neath Port Talbot Coll / Abercrave), Ellis Wyn Benham (Blues / Ysgol Glantaf / St Josephs), James Whittingham (Blues / Cowbridge Comprehensive), Steffan Evans (Scarlets / Ysgol y Strade / Kidwelly), Aled Summerhill (Blues / Coleg Morgannwg), Jack Huntley (Blues / Coleg Morgannwg / St Peters)
Wales Under 18 home fixtures 2013
St Helens, Swansea
Wales Under 18 v Leicester Under 18
Tuesday 12 February 14.30
Wales Under 18 v France Under 18
Sunday 24 February 14.30
Wales Under 18 v England Under 18
Sunday 10 March 14.30
Tickets: adults £5, Under 16s free, tickets available from Swansea RFC and by calling 01792 424242