Online learning may have been around for quite some time, but education technology (EdTech) as an investment option on the ASX is only just starting to take off.

There are any number of childcare centre operators trading on the ASX, but education services has lagged, even though revenues from online learning are forecast by some to more than double over the next five years.

Worth $120 million, 3P Learning (ASX: 3PL) is the largest, followed closely by Retech Technology (ASX: RTE) at $100 million, which is buoyed by rising revenues and is soon to pay its maiden dividend. Operating in the vocational education sector in China, it is targeting expanding into adjacent product verticals which should drive revenues and earnings growth.

These two both tower over ReadCloud (ASX:RCL) (worth around $35 million) and Schrole (ASX:SCL) ($15 million).

Thorney group members have a large holding in ReadCloud and it recently took part in a raising by start-up tutoring outfit Cluey Learning, although when — and if — it will come to the ASX is too early to clarify.

Given its size and prospects, Retech has recently won support from Pitt Street Research, which reckons Retech shares could be worth as much as $1.49, well ahead of the 40c or so they are fetching in the share market at the moment.

Retech provides e-learning services not just via the Internet, but also via other delivery platforms such as mobile phones and social media, to large corporates such as Mercedes-Benz, McDonalds Corp, Huawei and Bank of China.

It recently bought a local language school, and is keen to expand its software-as-a-service (SaaS) offering, while targeting other markets in Asia, with Hong Kong. It also recently entered into a joint venture with a Japanese e-learning operator.

Education is big business in Asia, with parents keen for their children to be well educated, with almost mandatory participation in after-school ‘cram schools’ in Korea and Japan, for example, providing another growth option.

“It has good potential,” says Pitt Street analyst Marc Kennis says of the outlook for Retech. “Along with the general education sector, it has a lot of corporate clients, producing ‘on-demand’ services such as introduction courses for new employees.

“It is also well aware of governance concerns of some investors towards some Chinese companies, and has an Australian advisor helping it with some of these issues.”

Launched to supply school text books online, ReadCloud has also expanded into the vocational education sector for another leg of growth options. It boasts the Thorney group as a large shareholder

ReadCloud raised a modest $2 million via a share placement mid-year, which was priced at 36c, and has so far sat out the rallying share market of the past few weeks.

Schrole occupies a different part of the education services, helping international schools locate staff, which can be a huge challenge. And with limited competition, it is enjoying accelerating revenue growth which augers well for a shift to cash breakeven, which could trigger a share market re-rating.

3PL (ASX:3PL), while the largest in the sector on the ASX, has been out of favour with investors amid flat revenue. It has revamped its push into the key US market, but flatlining earnings and a high level of ‘churn’ on some of its new business has investors wary.

Still, the shares rallied hard mid-week, pulling them out of a lengthy downtrend which has seen the shares fall to long term lows around 83c in recent trading, before bouncing 7 per cent Wednesday.

It is trying to shift negative investor sentiment by announcing recently an accelerated growth strategy which has also involved revamping its push into the US market which it is eying for substantial growth.