Tuesday, October 09, 2007

Less & Lotts

Lott's Bricks again, and obviously a different set from my previous Lott's post, with brickwork patterned pieces, and fancy doors and windows.

It's been a while since I posted here, and I apologize. I built this quite a while back, but lost whatever something I seem to need to post. I will try to return to posting more often, less perhaps than I was a few months ago, but more than I did in the interim.

I think I could benefit from some good block play.

Tuesday, July 24, 2007

Buncha Blocks

I have mentioned Buncha Blocks here before, but hadn't shown them. The red pull cord in the picture above is my replacement (as is the squeeze clasp), so my two bags are easily distinguishable since this one contains the Froebel Gift 6 pieces, and the other contains the balance of the two merged Buncha Blocks sets. I wanted to be able to grab just one bag without having to check.

Portable construction, on beaches, in parks, alongside streams, is the intended mission for these. They are shown in just such circumstance at Golden Gardens Park, enjoying a little sunshine this morning.

Unfortunately, I didn't inspect my plan folder before leaving the house, and it was missing the Froebel Gift 6 example plans. So what you see is actually an Ankerstein plan sheet, which requires arches which weren't with me. I probably will be rethinking the contents as I go, since I would like the contents of this bag to be as fun and versatile as it can be for "one bag builds" (cf the "one box builds" I was blathering on about a bit earlier today). A pair of arches are likely in the offing.

Both bags will reside in the car, and will be combined when the mood strikes me.

Sunshine & good block play.

Sad Addendum: These blocks mildewed and were ruined when the bag became wet without my realizing. I wonder if rubberwood is more prone to that than maple? [4 Dec 2009]


The Ankerstein folks have a new set on their web site that got me rather excited as soon as I saw it: a new version of the wonderful Heinzelmännchen set, which I only knew from instruction manual scans on CDrom and the related download site (Downloads: SPECIAL : HEINZEL).

The Heinzelmännchen patterns have delighted me, with their fanciful little elves or ghosts and intricate background designs, since I first found them - be sure to click on the sample the right, to get a larger view, and if you like that, download the rest.

But the second thing that jumped out at me was that the block arrangement shown on the Ankerstein site above is almost the same as the Kleine Gernegroß (that is the German spelling for Gernegross, by the way) I have been enjoying, and previously discussed here. It differs only in the addition of two stones, which turn out not to have been in the original anyway - presumably they were added to make the new version fit in the same box as the Ankerstein sets 4 and 4A.

Filled with delight, I immediately printed myself a new set of Heinzelmännchen plans, not willing to waste any time looking for my old set, and began building with my Lil' Whippersnapper. Whereupon I got my next surprise: the block colors are different! The Kleinegernegroß and new Heinzelmännchen sets have a different color mix than the old Heinzelmännchen, and thus don't match the plans, even though the old plans are shown with the new set on the web site.

It turns out the set isn't actually in production yet, so maybe Ankerstein will correct that error before shipping. I hope so.

In the meantime, it was awfully hard to resist the temptation to borrow the "correct" color stones from my #6 set. But I think I managed for these two pictures, at least. I wanted to show HM plans built with KG stones out-of-the-box, no fudging. It was a real struggle with my Asperger side, which wanted to duplicate what was shown, as closely as was within my means.

For a long time, I have contemplated buying a #4 set, for those times when a #6 construction was more than I wanted to tackle, but the #4 is expensive, everything in the #4 manual (which I had printed for myself from the above sources) can be built from a #6 set. (Set #4 construction at right.)

Lately I have been thinking again about the importance of "one box builds" - how sometimes it makes a big difference that something can be built entirely with the contents of a single set, with no supplements or rummaging around for extra pieces. It can also be helpful if the "one box" doesn't overwhelm with extra pieces, which is why the #4 set kept nagging at me, and why I was so quick to get the Kleine Gernegroß. The latter is nice, and I am glad to have it, but those small stones are a bit much of a challenge for me sometimes, so I am going to get a Heinzelmännchen as well, so I can enjoy the comfortable big blocks when I am ability-challenged.

Good Block Play.

Tuesday, July 17, 2007

More unit blocks & Froebel 6

I guess today is cat day in Blockplay land. Though in both this and my earlier fischertechnik post, the constructions are supposed to be the primary subjects, I know there are some who will enjoy seeing Archie more than my projects - and will be demanding equal time for Webster!

The two larger models both use the full Froebel #6 sets, though there maybe substitutions, it has been a few days since I built them.

The smaller structure at lower left was built from a subset of the Froebel 6.

Having lots of different blocks to build with can be fun, and can be liberating. But it can also be intimidating. For younger children, and for those of us with developmental disabilities, whether they are full time limitations or intermittent periods of recovery from recurring autistic regression, it can be helpful to select at a subset with a limited number of blocks, of an even more limited number of types.

A very good sequence is the Froebel 4, followed by the Froebel 6, followed - in due time - by a little more variety.

All my best toys offer multiple levels of play: an easy level for regression periods, or for reentry after a period of neglect long enough to forget some of how to play with them, a medium level for regular use, and advanced level - partly for occasional bursts of enthusiasm, but mostly so I don't feel constrained at the intermediate level: I know I am there by choice.

I consider that one of the key secrets of Good Block Play.


The image above shows a variety of operating models from different fischertechnik sets, under Archie's supervision. Right front is a carousel from the former Universal set, left front is a windshield wiper mechanism from the older (but still new style) Basic Mechanics set, while the larger amusement park ride in back is from the current Universal II set. All operate by turning cranks - the rides via bevel gears and drive shafts, the wipers via an eccentric crank.

The gray-block scale at left is a from an early 1970s set 50, while the black-block hut next to it is again from the Universal II.

The conveyor belt model at lower right has a more complicated lineage - the plan is from the caterpillar track expansion set for the old Master series, but it expected most of the parts to come from the core Master set, which I don't have. Not a problem at this point: I could borrow all the parts from sets I do have - in the correct colors, except for the X-strips bracing the vertical elements, which I had to borrow from on older gray-era set. The horizontal braces are from the same source, for color match,.

It's a fun model: you stack 30mm blocks in the vertical rack, turn the crank, and the blocks feed onto the conveyor, move across to the right end, and are dumped off. I should have borrowed a toy wheelbarrow from my wife to pose there to catch them. Or better yet, built a wheelbarrow from the old 1960s manuals - though it might have been too high.

Aside from having to scrounge the parts, this was the most problematic ft plan I have done yet, with part count inaccuracy and the finished model showing a tendency to malfunction (I straightened cattywumpus blocks for the photo). It was still fun.

I haven't done a fischertechnik construction yet that wasn't Good Block Play.

Friday, July 13, 2007

Unit blocks & Froebel Gift #6

Among the Froebel Gifts, the blocks in the Sixth Gift show the most promise for being fun to play with. But this hasn't seemed to necessarily translate well into print. I think the biggest problem is the Froebel rule that all blocks in the gift be used in each construction. I do much better in free play when I allow some to lay on the table, and better still when I have a few extra to supplement here & there.

The secret here is probably to build something from a design sheet, but when it is finished - or even before - break loose and build freestyle, using the starting design simply as inspiration.

The design in the photo is from Bauen nach Fröbel - Vorlagen und Anweisung, by Friederich Seidel, Vienna, 1890. I downloaded the source image at right in January, 2005, from - I believe - a Japanese site which doesn't seem to be there any longer, so I can't request permission to share more of the 10 pages of diagrams for Gift #6 (source corrections or updates welcome). Though they tend to be repetitive and with many artist errors, they are still interesting and potentially useful.

The image at left is from Royal Gifts for the Kindergarten, by Frances Post van Norstrand, Chicago, 1888. You may recognize design number 7 from an earlier post here, though it in fact was done from a different book - the Royal Gifts designs are a subset of those in the Wiebe book cited in my recent Gift 4 post, albeit with new art.

Compare the Gift 4 designs in the Royal Gifts scan at lower right to those in Wiebe to see the similarities. I include this scan not just to illustrate my point, but so that those wanting a compact and simple set of inspirations can print out the two single-page Royal Gifts sheets (click on the images for a higher resolution version for printing), perhaps laminated back to back for durability and convenience.

For building to the Gift 6 designs, as well as Gift 4 and a good deal of freestyle fun, I suggest IQ Preschool's "Buncha Blocks." The sets come with nice canvas carrying bags, and I divide my two sets so that all the Gift 6 style blocks go in one bag, all the other blocks (arches, dowels, planks, triangles, semicircles) go in the other - they come out almost exactly even in bulk. While this means 16 of each of the three shapes are in the Gift 6 bag, instead of the 18 + 12 + 6 of the formal Gift 6, only the strictest Froebelian formalists will suffer much. Since two of one or the other of the alternate shapes can always be made to substitute for the "oblong block" (Froebelian terminology) or "unit block" (unit block terminology), there is no constraint on building by being two short in this shape.

Whatever the blocks, whatever their size, Froebel's Sixth Gift is a fine entry point to Good Block Play.

Wednesday, June 20, 2007

Lott's Bricks

Lott's Bricks were an English toy, apparently manufactured from 1918 through the 1960s, notwithstanding a 1911 copyright date prominently appearing on boxes and manuals throughout their existence! One story is, Lott's took over the British operations of Ankerstein manufacturer A. Richter during World War I. But the blocks are not Anchor Blocks - the composition is noticeably different and the size is slightly larger - based on an imperial inch of 25.4 mm versus a metric inch of 25 mm.

In some ways, I like the Lott's material - slightly slicker & apparently sturdier than Richter's - the pieces are in much better condition than older Richter's tend to be, in spite of obvious signs of having been played with. But I miss the characteristic linseed odor of Richter's, and am inclined to believe that the latter's rougher surface makes for sturdier large constructions. [addendum - I may not have noticed the linseed oil scent on the bricks, but after spending some time handling the Lott's manual, I notice the scent on my fingers!]

I didn't get the Lott's set for large constructions though, but rather for the charming smaller constructions - in fact, my primary interest in buying the set was the manual not the blocks! The booklet with my #1 set includes plans for sets O, OA, 1, 1A, and 2 - and the parts in set #1 will build any of the O or OA plans, as well as the set 1 plans. There is a lot of nice contrast to the typical Anker constructions.

This "goods shed," or railway freight house is from the OA plans, all of which are shown on the illustration page, though I have only included one of three pages of plans - be sure to click on these images to see the full size scans, especially the illustration sheet is a pleasure to behold. (I will share additional pages in the future.)

All of the blocks correspond to shapes in Richter sets except for the chimney base which is used here as the middle support under the loading platform. There should be two in the OA and #1 sets, and of course one of these was the only piece broken - with one of the broken halves missing! [Attention Lott's collectors: Anyone have a spare?]

I am contemplating supplementing my unit blocks with some homemade pieces to be able to build the Lott's designs large, in wood.

Even if I do, I expect my Lott's set will be getting quite a bit of use, and delivering quite a bit of pleasure.

Lott's Bricks are classic Good Block Play.

Ferris Wheels

Last week I did a fischertechnik ferris wheel from a 1990s set, a few days later I wanted to build with Engino, and ended up building another ferris wheel, partly for comparison, partly because I needed to work from instructions, and there aren't that many options yet.

The representation of the two models shouldn't be too directly compared, since the fischertechnik is a single-model kit, while the Engino is one of many models which can be built from its set. Usually, I would score that heavily in advantage of the multiple-model set, but there are only standard-mix parts in the fischertechnik set, no special or oddball pieces ala Lego. The main stretch is the inclusion of twelve of the 60 degree curved sections, which are created by using a curved side section to form a straight beam to a curve. FT's multi-model sets, like the Universal II, usually only include a couple of these. I do wish that FT had included twelve straight side sections as well, so the beams could also be used more conventionally.

I already knew that fischertechnik was head and shoulders above Engino in quality, but this exercise really emphasized that. Piece by piece, connection by connection, instruction by instruction, the quality difference stood out. It's not that Engino isn't satisfactory - part quality ranges from adequate to very good and there are only a few slips in the instructions that drop below adequate. But fischertechnik may well be the best quality toy available, and surprisingly enough there isn't that much of a price premium, if any.

For some purposes, I recommend the Engino 60 set over fischertechnik - there is less learning curve and the "fiddly bits" (small pieces) are neither as small nor as numerous. But for anyone wanting to make a long term commitment and get the maximum benefit in return, fischertechnik is the way to go.

Most importantly, both are good block play.

Thursday, June 14, 2007

Unit Blocks & Froebel Gift #4

The Fourth Froebel Gift consists of eight oblong blocks which relate to the cubes of the Third Froebel Gift by being half as thick, the same width, and twice as long.

That 1:2:4 ratio is exactly that of the Unit Block which have formed the basis of Unit Block (or "Kindergarten Block") sets since 1914.

So, while I often do ift #4 exercises with the specified size blocks of 12.5 mm x 25 mm x 50 mm, I am also inclined to grab other blocks of the same proportions, and most often, those are Unit Blocks.

Going the other direction, if you have some Unit Blocks, and are looking for some basic designs to build, the patterns that appeared in old guides to Froebel Kindergarten activities are a very good start.

You can build them strictly by the rules, with just the 1:2:4 unit blocks, of you can use a mixture of half-units and units, as I did in the photo at top, a choice which may be forced on you by the occasional tendency of modern Unit Block sets to be somewhat sparse on actual Unit Blocks.

I have included here all of the Gift #4 "Forms of Life" included in Edward Wiebe's Paradise of Childhood, of 1869 (mine is a 1907 printing of the 1896 edition; recently reprinted in paperback), where the author acknowledges that "the plates accompanying this work are reprints from 'Goldammer's Kindergarten,' a book recently [also in 1869!] published in Germany."

The plethora of designs for the various Froebel Gifts that were widely published in a variety of books (in many languages) may have been a key part of the downfall of Froebel's style of Kindergarten: the designs were taken by uninspired teachers as being prescriptive, ignoring Froebel's intent that the designs be mere examples, and that the children should construct "forms of life" that had meaning for them, in their own lives. [See Inventing Kindergarten for more on Froebel and early Kindergartens.]

I think that in their reaction to that, the inventors of modern Kindergartens and modern Unit Blocks have tilted too far the other way, and ask us to do everything from scratch, rather than giving us some ideas and practice constructions to get us started.

With any design set, I suggest building some example designs to learn the syntax of constructing, then modifying the plans from ones own inspiration, and only then building entirely new creations. And even after exploring with full creative freedom, I believe returning to example designs, occasionally or frequently, can be an important process of the learning process.

Creative opportunities for modification or freestyle building can be enhanced by adding additional blocks, a few at a time, but I suggest starting with just enough to build the designs: 8 unit blocks, or if there is a shortage, as many unit blocks as are available, and two half-unit blocks in place of each missing unit block.

If more than eight unit blocks are available, then initial expansion of the play set might best be more basic units - in recent years, much has been made by having block sets consisting of blocks of all the same shape, such as Kapla or Dr. Drew's Discovery Blocks, and there is indeed some value in that, as Friederich Froebel discovered some time before 1836.

So click on each of the design sheets for a high resolution version, print them out, and enjoy some good block play.

Sunday, June 10, 2007

Bridges & towers

For several days I have been working on bridges out of K'nex. First, I built the odd looking thing at right from a 1997 K'nex "educational" bridge set. The bridges of that set seemed to have been designed from sketches of different bridge types, not from real bridges - which may be why K'nex came out with a larger, more accurate, and much more expensive "Real Bridges" set. It surely inspired the name.

After building that bridge "by the book" (or at least "by the card"), I more or less duplicated it using longer K'nex rods, and omitting that truly odd support structure.

I continued to fiddle with it over the next several days, which included an excellent "research" (more accurately "inspiration") trip to a lovely Pratt truss on the Snoqualmie Valley Trail - the former Milwaukee Road Cedar Falls to Monroe railway line, converted in that segment to a hiking and biking trail.

I like the results (top). This version is about five feet long.

Today, I decided I had had enough K'nex, and it was time for some fischertechnik, so I brought out the Universal set again, and built this nice communications tower (left).

I've fiddled with a few short bridge trusses out of fischertechnik, and am just about ready to do something substantial. It may have to be a mixture of yellow and gray - a bridge in the process of being repainted?

Whichever direction I take with it, I am sure it will be Good Block Play.

Just as these projects were all Good Block Play.

Sunday, June 03, 2007

Stack play

Wooden blocks, rectangular mostly, being stacked on each other with nothing but gravity and friction at work. Outdoors, in the sun, on a lovely Sunday, with children at play.

The best kind of block play may well be stack play, even if lately I seem to have been mostly doing tech play (connecting things, especially with mechanisms involved). I've been doing pattern play lately as well, my third general category of block play (we'll get to that here again soon, I hope).

Today's outdoor exercise was partly inspired by some block construction designs I found online with a gaudy multicolor set of plastic blocks. I didn't like the blocks much, even if they were in legitimate unit block format, but the designs intrigued me - they are far more interesting than usually accompany block sets (click on image for a larger view).

So I printed them out, along with a guide to which blocks I would need, and made up an appropriate set from my unit block collection. It's actually a nice little set, once decolored - which shouldn't come as surprise given the quality of the constructions.

Once outside, I soon discovered that the concrete stepping stone I intended to use as a building surface was too uneven, so I built the cathedral on the box lid - which sagged, giving us a bit of an A-frame effect.

My neighbor offered up a sturdier foundation, and her younger girl offered assistance. Assistance quickly became supervision, and I found it best to sit back while she created "a whole family of houses." It was well worth the interuption to see real early-childhood block play in action. She's also a sweetie.

Once she moved on, I was able to go back to building the old fashioned gas station (top), followed by the chair & table, and the dog - though she did return periodically, demanding explanations as to what I was up to. She was especially concerned as to what dog that was.

Great block play.

Wednesday, May 30, 2007


This is one of the four Engino designs with full instruction requiring all four Mini-Packs or the Engino 60 set. I am usually not tempted to build dinosaurs (or is it a dinosaur-robot?) with technical sets, but I have been curious about the usefulness of Engino's adjustable components, and this obviously made use of them.

All in all, I would have to say that this model went together somewhat badly. The instructions were unclear, and in at least one area, a substructure simply will not fit in the manner the computer-generated instruction images depicted. For the final step of connecting the major subassemblies into the final beast, I had to study the diagram with a magnifying glass to work out where to connect what. I probably would have been happier if I had started using the magnifier earlier.

And once it is together, it turns out that when you raise the tail, the mouth closes.

The adjustable components? Not quite adjustable enough to avoid needing to warp some assemblies to make them fit. I had wondered how adjustability could be so valuable in over-nine-unit lengths, but unneeded in smaller lengths (where the percentage difference becomes much greater), and of course that turned out not to be the case: in several smaller assemblies, a half-unit adjustment would have been quite handy, perhaps even a quarter-unit.

Half unit length steps can be achieved with existing parts by using round red hub/pulley element as a beam extender, though a new part with square cross section to match the beams would be welcome. (Why does Engino call the common yellow structural elements rods? It is technically incorrect and tends to suggest a K'nex inspiration for development of the Engino system. They are more like box girders. I'll stick to calling them beams.)

The quarter-unit adjustability of the expandable component could be achieved more elegantly with a 3/4 unit beam, if it is actually necessary at all (it would violate the educationally sound length-doubling sequence of the other parts - which of course the adjustable component already does). There is enough clearance in the single unit beam to allow a shortened version, though providing enough flex for easy connecting and separation might require some creative modification of the slot - perhaps a lollipop shape?

Of course half-length and three-quarter-length pieces might more elegantly solve the engineering need, but they wouldn't look nearly so fun for marketing. The "expandable rods" may be gratuitous gimmicks from the versatility point of view, but they are cute and clever, and to be fair, they make great-looking simulations of hydraulic actuators. aLl in all, they may not live up to the hype, but they don't do much harm: Engino is still an attractive system.

And for all the shortcomings in this "dinobot," Engino is still good block play.

Tuesday, May 29, 2007


K'nex has been around just long enough - 15 years - that it may qualify as a classic, but if you haven't taken a look at it lately, you might be in for some surprises: Micro K'nex and K'nex bricks, for example. Also a new logo: bolder and more angular against a black background - not so interesting in itself perhaps, but in a store with a variety of K'nex sets, it can help steer you to the ones with micro & bricks.

The micro K'nex are 60%-size versions of classic K'nex parts. Since their first announcement, I have been hoping for a pure-micro set - a "pocket K'nex." But no such luck: so far they are just appearing as supplemental parts in regular sets, with bottle-shaped adapter rods to connect to micro to regular. In exchange for the special features they add to the models that use them, there is some cost in robustness. Smaller connections just can't be as sturdy as regular K'nex: The wind kept blowing over my windmill during my Gasworks Park photo expedition, and if the tumble was very far, I found reassembly required and occasionally had to search through the grass for tiny missing parts.

The K'nex bricks are compatible, brickwise, with the usual suspects, which provides some interesting combination options. Unlike most similar products though, K'nex bricks have rounded edges which provide easy fingernail purchase for separating connected bricks. All bricks (that I have seen so far) have holes for 5mm peg connectors, for either micro or regular K'nex. Which is just shy of being compatible with the similar holes and plug connectors of Lego Technic (and some regular Lego). Sigh.

The set I got to try out micro & bricks came in a new case design that was sufficiently warped that most micro pieces could conceivably find their way out the gap. Worse, it takes no advantage of the new brick connection options to provide a buildable surface. Sigh again.

However, there were more pleasures than disappointments. With or without the new parts types, K'nex remains Good Block Play.

Monday, May 28, 2007

fischertechnik Universal

From their introduction in 1965 until 1990, fischertechnik blocks were gray, with red supplemental parts, as is seen in the wrecker here. Gray was also used for the beams and strips, introduced in 1970. After 1990, blocks became black, beams and strips yellow, which combined with the red to be a little much for me. But after long resisting the gaudiness, I finally succumbed.

For a techno-geek, fischertechnik's Universal sets are almost irresistible. Well, maybe not "almost." The original Universal was introduced in 1994, with 450 parts of 119 different type, to make 24 different models. It was replaced in 2005 with the Universal II, which makes 48 models from 400 parts of 98 types. 21 of the models from the first set were carried over to the second, and it appears that none were "dumbed down " - instead, the designs are just that little bit cleverer at using common parts.

That original Universal was devoted to demonstrating how basic technologies work, such as in the garage door opener shown here, which works by turning a crank at the back - instructions are included for adding the optional motor. This model went together easily, works smoothly, and left me encouraged to try something more complicated. What more could one ask for? Ummm ... perhaps a little more glamor? The set was popular for classroom use, but may have lagged for home play. The new version adds vehicles and aircraft, and increases the number of fairground rides, for a bit more "wow factor," and perhaps more play value as well.

fischertechnik is sometimes described as "Lego for grownups," which isn't fair to fischertechnik's sets for five year olds, or nice range of products for seven and nine year olds. But they do make products for use in technical universities, their robotics sets have long been greatly admired both in schools and by advanced adult hobbyists, and their parts have been used for industrial prototyping since very early on. It's not that they aren't great for grownups, it's just that kids don't have to wait.

An excellent choice for a clever child, or for a child that might become clever with a little nudge and some Good Block Play.

Saturday, May 26, 2007

Ankerstein 6A

Anchor Block box 6A is the supplemental set to expand a set 6 into a set 8. From there, one would get an 8A to create a set 10. Only plans for structures using combined sets 6 and 6A are included with 6A, and only plans for combined 6, 6A, and 8A are included with 8A. The buildings just keep getting bigger and more complicated. My abilities, however, don't keep getting more advanced. I use set 6 much more often than I use set 8 (6 + 6A).

I have long wished for even a few plans that just use box 6A, without set 6. The number of stones would be more manageable for me, I would have more opportunity to enjoy the new and different stones introduced with set 6A, and I would have a new variety in play without making greater demands on my abilities.

My recent acquisition of the new pocket Ankerstein set brought this desire back to mind, and today I took out the 6A box, and built an ad hoc building using just stones from that box. It's not a great design, since I was working it out as I built, but it is not bad, and I am quite pleased. I know I will be doing this again in the future.

I'd still like to have a few plans though, so if anyone is up to the challenge of working some box-6A-only or box-8A-only designs up either in photos or in AnkerCAD, I would be hugely grateful, and I'm sure their are others who would be appreciative as well. I haven't used AnkerCAD for a while, but as I recall, it doesn't have an inventory feature, or at least doesn't have a function to restrict you to only the stones available in a given set, combination of boxes, or loose stones. I needed that badly.

It wouldn't take very many plans for box 8A for me to justify purchase of one - I couldn't justify it at all to just build set 10 (6 + 6A +8A) designs, I would do that so rarely.

In the meantime, I am rather pleased with what I have accomplished today, both in breaking new ground and in Good Block Play.

Monday, May 21, 2007

Odd Jobs

Usually I show current activity in my blog posts, but this is a bridge I designed and built a few years ago, from Eitech parts. It illustrates the use of adjustable length parts to solve a design problem, where using a standard length part would have severely disrupted the curve of the arch. Adjustable length parts in construction sets have been around at least since Richter's Anker bridge set of 1895, and are still a regular component in sets from Eitech and Merkur and perhaps others.

But in this bridge, as in the Engino bridge I built yesterday, I find the adjustable parts are not entirely satisfying.

First, the parts represent bridge members that would be under compression (forces push on the ends - the member must not collapse), but the parts have the appearance of tension members (forces pull on the ends - the load might instead have been handled by a cable). When you look at the tower crane in an image from the Engino box, the upper, diagonal usage of the expansion parts looks reasonable - a cable would work here; while the lower, vertical usage as a kingpost is more doubtful, though not as bad as the bridge. In the adjacent suspension cable car (have I identified this correctly?), the parts look fine to me - such vehicles typically use lightweight components where they can.

Second, I am not completely comfortable with the use of adjustable "building blocks." A good portion of what a construction set should provide is exercise in solving problems with standard elements. Deviating from this, whether by adjustable parts such as this or the provision of new ad hoc parts designs (Lego is especially egregious), reduces the "puzzle pleasure" and may also reduce the learning value.

If a child is playing with a set that has only limited positions for fastening parts together, meaning that only certain choices for two sides of a triangle can provide for an appropriate third side allowing for a right triangle, he or she may not rediscover the Pythagorean Theorem, but they will at least have some context for recognizing that the Pythagorean Theorem relates to the real world. Will they get this, if they have solved all their triangle problems by simply readjusting the expandable part?

Further, are we then teaching them how to create and adapt and problem solve within constraints, or are we teaching them that the world will adjust itself to their needs and expectations?

Block Play, at whatever level of literalness or metaphor, is importantly an exercise of balancing constraints with versatility.

A construction set, if it is to be both enjoyable and educational, needs to balance those demands of constraint and versatility. Each constraint can have both pros and cons, and each versatility can have both pros and cons.

The Eitech sets, the Merkur sets, and the Engino sets, with or without the expandable parts, provide a variety of trade offs of constraint and versatility. Each, I believe, provides more pros than cons, and each is a worthy candidate for good Block Play.